I think the only thing we were uncomfortable in 2 years ago was squeezing me (then a 14), DH (then over 300 lbs and 5'10"), and our 1 year old, into Dumbo.
That was perhaps NOT the best idea ever.
Last year DH tried, but didn't end up going on astro orbiter; he thought he was getting in that line, but got in the Buzz line instead. So this year will be our first experience with Astro Orbiter, assuming we find the right line.
I remember being on a ride or two last year or the year before, where the difference between my legs and DH's big sumo wrestler legs (and I was more than a 14 last year, unlike in '05) seemed far too big. I didn't like being as airborne as I got on those rides.
But anyway, last year at a 20ish I had no problems with not fitting into rides, and DH hasn't had problems other than worry or just having things be tighter than he wished (nothing like having a weight-related existential crisis AFTER you get to
Disneyland!), though he's over 300 and is on the shortER side, being 5'10". And he's big-bellied, big backed (the pix my brother took from the ground of Dumbo have almost all been deleted, b/c DH would have cried had he seen them....do NOT have someone taking a picture of you on that ride if you have a broad, heavy back), and has big sturdy legs, so he carries the weight everywhere...but still, no actual problems.
(this was at DL itself, we haven't yet been to DCA)