I like to ride longer rides (30 miles) for leisure and exercise, and I have been riding my new 58cm Soma Saga for a month now. This bike was selected after riding an older Kona cross bike as my road bike for years, which had a terrifically stiff frame and fork and rigid wheel set. The Kona was great for a half hour ride, good for an hour, and abusive and harsh for two or more hours. Tried saddles, tires, shoes, gloves, but it was simply too stiff of a frame; too straight of a fork; too short in the rear end; and too responsive to steering input in the front. I decided I needed a touring or light touring frame, and I wanted steel for the ride characteristics I had always enjoyed on my old road frames and mountain hard tail frames. I was also hoping for something "affordable," which I guess is around $2k built these days.
I test rode LHTs (disc and canti) and a 520, and a new Vaya. The LHTs were fine, but did not feel as lively as I imagined I wanted an all-day bike to be. To me, they are like a pickup truck: great at what they do, but really, most of the time a minivan is quicker, hauls nearly as much just as well, is more efficient, more agile, and just as comfortable as a big truck or SUV. And LHT felt slower than the Saga, although i have no evidence of that, it was just an impression. The Vaya was nice but reminded me of my cross bike too much, with that straight fork and seemingly harsh ride, and for the same cost I felt I could go with an affordable steel touring frame set and get it custom built. I liked the 520 for ride quality but felt I would spend the next year upgrading one thing or another, like wheels, brakes, bars, bar tape... So I opted for a Soma Saga frame, after considering the All City Space Horse as well. It was the sloping top tube that made me pick the Soma over the Space Horse.
The Soma Saga has a long head tube, more upright ride, and is stiff enough in the bottom that I don't feel or notice flex. And at my size ( I am 6ft 215lbs.) I always seem to flex the BB. That is one reason I ride an old Klein MTN bike frame: no flex.
I am using a SRAM Apex 2x10 setup, pauls canti brakes, SOMA Off-road drop bars, and VO Touring hubs/velocity rims. Right now I am on 32 Schwalbe Marathon green guard tires, but will play around with some Continental Gatorskins that may roll easier and be nearly as flat resistant at substantially less weight. Built like this I have no problem on rough roads, gravel roads, or busted up city pavement. And it rides SSSOOOO much better than my old Kona Jake cross bike on the same routes! I plan on doing longer training rides this summer with it, with a few century rides and a season-ending supported charity weeklong tour across Montana. I don't foresee doing fully loaded tours but 35 lbs for a couple nights? Sure. If fully loaded comes around I may need a triple and lower gearing anyway.
One last thing about upright position: I was just about done with drop bars of any kind when heading down the touring bike path, and considered uprights with bar ends or trekking bars as my only way ahead. I don't like or prefer to use traditional drop bars, and struggled with comfort, position, width, for years. My local bike shop owner and builder offered me a ride on his personal road bike that had Soma Junebug off road drops, and it was a revelation! I now use the drops, the brakes and shifters are always at my fingertips, and they are comfortable in any position. Totally natural and intuitive from the first time I tried them. Just a thought.
Good luck with your search and decision.