Let's contemplate my posterior for a moment....
 

After my 30 mile gravel ride yesterday, I could barely walk. This morning I feel like I have two badly bruised bones in my posterior. So what's the best way to go about getting your rear end fitted for a saddle? Do I buy a piece of cardboard and sit on it? Do I visit a bike fitter? Do I ice the cheeks after every ride?

Help, I need answers!

Saddles are probably the most personal item on a bike. You can get measured for the width(and there are plenty of ways to do that yourself if you like; but most bike stores can do that for you). The big trick is finding a shape and firmness that works for you. Some people like quite swoopy saddles, others (like myself) like very flat ones. Almost all saddles have some form of relief cut out/depression to relieve pressure on the tender bits.
A good bike shop will have "loaner" saddles that you can try (or a good return policy) to help you find the right saddle for you. I can rule a saddle out in 5 minutes of riding, but it normally takes me a good 40 or 50km long ride to decide that a saddle is right for me.

If you're seriously saddle shopping,use the resources at your local bike store and then buy from them. This is a service well worth paying for.

Have you ridden that route before?
if not, what's different from your usual routes?
if so, what's different from usual rides on the route?

30mi of riding isnt something i would think would cause bruising the next day. Perhaps something is different from your usual gravel rides.

How long have you been riding? Have you had these issues before the 30 mile gravel ride?

Glutes are often sore if you have not ridden in many months or years. Could be just normal muscle soreness and pain from pedaling, and nothing to do with the choice of saddle at all, especially if there is no bruising or chafing.

We'll need some pictures for an accurate diagnosis.

(my experience inserted, possibly no relevance to current situation)
on my road bike, i sit through pretty much everything. Thats comfort. Now, i tried riding gravel once and i was like bruised! left me wondering..... a fellow rider lent me his mountain bike and asked me to ride it down a hill - he immediately noticed what the issue was! my a$$ was glued to the saddle and my knees were not providing any cushion. A few practice rides and now, uphills, i am slow enough not to hurt, downhills i use my legs to cushion and as lil pressure as possible on the saddle, flats i move around forward/back, just a little not to be sore.

I did the measure your sit bones and purchased a saddle based on those measurements. For what ever reason I had zero issues with my backside last summer and I even tried to induce some discomfort, e.g. 37 mile road ride wearing regular cargo shorts (no padding).

But just my luck I went to buy the same saddle for my new bike and it's no longer being manufactured. I'm hoping the saddle I purchased for the new bike works as well for me as the saddle I have on my old bike, we shall see.

No we don't.

Well, the thing that was different is that there was a lot more mud than usual.

It's not the glutes. I ride on average 60 miles a week. I usually ride 15 miles out, get off the saddle, get a drink, and then in a minute or two, head back 15 miles. The last two times I have a lot of pain when I put my butt back on the saddle and start back on the final 15 miles leg, more pain that I had when I first stopped. In other words, it's when I stop, get off the saddle, and then get back on that I have a whole lot of pain. Yesterday it was so bad I'd almost call it excruciating for the nest 15 minutes. After a while, the pain subsides a good bit. This morning it felt like I had bruising on the butt bones, two behind each cheek.

I dunno, maybe stand up more. It's counter-intutitive, but how soft or big a saddle is has little to do with comfort, at least for me. If it mattered, I'd be using a tractor seat, but that's not a road I care to travel down. I think shape matters most to me, but fortunately, I'm not that picky about saddles, as long as they're level, quiet, and not too big or too soft.

HTFU and get a Brooks saddle. And stand up on the pedals a bit.

buy an azub max recumbent bike full suspension...you will never have an uncomfortable ride ever again

Does it do singletrack?

That's what I have now, a Cambrium.

The Brooks Cambium seems pretty hard to me when I've checked other people's bikes. They like 'em but they're riding only 10-20 miles, very casual, with lots of stops. I'm not sure the no-break-in philosophy works quite as well as a fully broken in leather saddle.

Try padded shorts with denser padding. The best I've found for firm saddles over rough terrain on long rides is Przewalski 3D padded shorts -- very affordable too, around $15-$30 for shorts or bibs. The padding is unlike anything else I've worn or seen in shops -- smooth surface with dimples like golf balls, thick, dense and resilient. It's well suited to a somewhat upright riding position -- less comfortable leaning forward in the drops or onto aero bars, at least with my firm Selle Italia saddles. But for longer rides on the hoods or tops, or my hybrid with albatross bars and unpadded saddle, it's fine. (Regarding the one complaint I've read about the padding deteriorating, the user didn't specify how he washed the shorts. I usually hand wash my bike clothing in tepid or cool water and hang to dry, or in cold water at gentle cycles in machines, and low temp drying for the minimum time it takes to dry. I've never seen any cycling clothing fall apart, although logos eventually peel off many lower priced jerseys.)

A slight adjustment in seat post height, fore/aft saddle position and angle can make a big difference too in comfort over long distance or rough roads.

try a no $ fix first. Lower the bars a 1/2 inch and ride the same route. That may tell you it's just an adjustment problem (and possibly seat instead)- but at least you'll have more info to work with before spending money in maybe the wrong direction.

Have you tried any of the leather ones?

Cambiums hurt my arse.

I don't know much about the Brooks Cambium, but, FWIW... I only ride leather with no padding, usually just 2 layers of Lycra. Shorts and base layer or just 2 pairs of shorts. It really allows for good airflow and keeping things dry. But leather can be softened with mink oil or similar. People caution against doing it as it will shorten the life of the saddle from 20 years to 10 or so. But, once they are supple and conformed to you, nothing is better IMHO.
Now... I had to harden the heck out of my posterior to do so. And there have been times where I've had blisters due to having the tension too tight along with 100 mile days on mountain roads. If I do 30+ mile rides on successive days, I will start to get some tenderness. but it is not debilitation. I have some moleskin tape that does wonders.
Hope you get it figured out.

Everyone likes something different- flat saddle, curved saddle, wide saddle, narrow saddle, etc.

If C17 saddles werent so expensive, i would have them on all my gravel and road bikes. Love em. Love em for 10mi rides, 30mi rides, 60mi rides, etc. Just fits great.
The no break-in works quite well as its simply a dense rubber shell that flexes a bit(like a broken in leather saddle) and doesnt need maintenance.

the thousandth 'what saddle'? thread, just this year . read any of the others?

My multi month bike touring saddle has been a Brooks team pro.. but when in town just doing my daily rides, I go Pleather covered foam ..

Try a few 'Take Off ' saddles from your LBS .. they're cheap, & you can try a number of them.. in sequence..

I've gotten a few nice ones taken off a used/consignment bike ... new buyer did not like it, bought a new one..

I just measured my sit bones, and I now have a new SQlab 610 Ergolux Active arriving Thursday, thanks to Amazon! I'm doing another 30 mile gravel ride late Thursday afternoon, so if Amazon delivers it early enough, I'll slap it on the bike and see how it does.

Last summer sucked (for my ass).

Tons of miles. Anything beyond my neighborhood hurt. I bought different saddles, expensive ones. Mixed lidocaine with my chamois cream, generally hurt. I finally got the adjustment right. Of course it happened after I'd done all my longest rides of the year, but hey, its right. I might stab a motherfxxxxr if he adjusted it now. This is an SLR with cutaway, not some super cush tractor seat.

If it hurts, something is wrong. Seat adjustment or seat. Or both. Keep trying. Don't accept a painful ride, you can get it right.

Something else to think about. My gravel bike has a two bolt seatpost, that makes it a ton easier to adjust. Like the Thomson but heavier. I got that one right in 2 rides. The road bike with the single bolt (almost) vintage Campy ti post, is the one that took all summer.

FWIW - The saddle on my old bike, the bike I put 565 miles on in one week (which included two centuries), is a cheap Nashbar Sport CF1 in 155mm. With Nashbar going belly up that saddle is no longer available.