I'll agree with Space Mountain. It can be pretty rough. As a flip-flop tourer, I have gotten my flip flop caught several times, always the left one. I think I may need to remember the turn over, knee on the seat routine. I've always put my hand on the seat in front of me, and gotten up that way.
Astro Orbiter I never had a problem on, but I've always flown solo
Yes, be prepared to pull yourself out. But it wasn't too hard to get out of.
Being 5'9", I encounter more rides where I may have to "shift" so my knees aren't right up against the ride vehicle. These include Splash Mountain, Snow White's Scary Adventures, and Winnie the Pooh.
Another one is definitely Rock N Rollercoaster. To avoid the knee issue, I ask to sit in an odd-numbered row. CMs are awesome about this and have never had a problem!
Spaceship Earth is another shifting of knees ride.
Another tight one may be The Muppets. I lower the seat, sit on the edge & work my way back.
A possible "eek!" is on Kali River Rapids. It can be tough if a CM tries to sit two-per-seat, as designed. But usually CMs are cognizant and will load the raft in such a way that it won't draw attention and such.
These are the only "issues" I've encountered, and tbqh, aren't issues at all. It's just "knowing" they will be tight on my knees, but never uncomfortable, especially if you go in knowing that you need to sit sideways, in order to not be knee-to-back. Never felt self conscious otherwise.
Someone did mention the Sum of All Thrills ride in Innoventions. My mother tried this, and LOVED it! She, however, is also pretty skinny. The queue has a sign that says something to the effect of, "not all body types will be able to partake in this attractions". I read on the boards that there was a weight limit, whether or not there was, I avoided it.
Have a super fun time!!