I've spent a lot of time working on just this problem and it's actually quite tough to solve. There really aren't any easy high quality solutions.
The best intercom solution is the
Terrano Systems stuff. We used the first version for years and upgraded to the new version this year. The noise cancelling is great, it's full duplex. We primarily use it for the two of us but it is also supposed to work with a total of 4 units but we've never done that. Range is about 0.5 to about 1 mile. The more line of sight it is the better it is. For the two of us riding, this is excellent which you would expect based on the price. We have been using their stuff since it first showed up as Cardo System (now spun off as the cycling stuff into Terrano Systems).
I've also worked with
Zello (a free walkie talkie style app) on the cellular phone. You will need to buy a
$20-30 PTT button to put on the handlebars or on a lanyard under your jersey, but it worked fine with an Apple AirPods earbud in one ear. This has unlimited range, unlimited number who can join a conversation but you have to be in a cellular data system. It uses very little data. The noise cancelling is as good as your bluetooth headset although you can improve the performance by adding one of the
Cat Ears fuzzy wind blockers to your helmet strap ($17 for a pair and help with most any headset in any system). This is probably the lowest overhead set up provided you already have either iPhones or Android phones for everyone AND you'll be riding in a cellular service area.
The third solution I've developed is using a
Baofeng BF-F8HP UHF radio ($60 on Amazon). The thing is a very small radio that easily can be carried in a jersey pocket. To this, I found a
bluetooth kit that replaces the speaker mic connection and a PTT button for the handlebars, and works with a provided earbud. This device is about $50 and I then bought this
nifty MPOW tiny bluetooth headset for $17 that fits almost entirely in your ear. In order to use this, you will need the free CHIRP software to program the radios - I set them up with GMRS channels in the US and when we cycle in the EU I switch to their analogous frequencies and reprogrammed the radios. This works very well in remote areas and doesn't depend on cellular but it does mean you need to understand a little bit about radios to set them up. It's a nice set up but you'll have to be competent setting up electronic stuff. Range is easily a couple of miles. Side benefit is that this is a set up that can work well for other activities besides cycling with our without the bluetooth earbud. But make sure you're comfortable with the 2-way radio technology to set this up.
All three of these solutions address different problems and we haven't found a solution that works for everything. Handheld walkie talkies are not a good idea - you have to find the stupid thing, get it up in front of your mouth, they are not very tolerant of wind noise and they would be a disaster for the kids to use while riding. Rudimentary communication at best and probably for most people shouldn't be used when riding.
Overall, I see what the OP wants to do. I ride a lot alone. When my wife and I ride together, it always felt like we were both going on two separate rides together. With the ability to communicate, it became safer, easier to coordinate movements in traffic, didn't have to worry so much about sticking close enough to yell back and forth, and it was a lot more fun to talk about stuff we were seeing. So I'd say that for riding together, this was definitely a good thing.
J.