Hi - I'm new here too!
I also have a weight related questio. I've always been 'big' but have always fitted in fine to the seats. But the last year I have been ill and put on a lot of weight due to low activity and respiratory problems.
Anyway I'm almost certain I am ok for the chest restrictions but when sitting down my stomach is 57" is that ok? My chest is 46" - not very proportional!
But is that ok? I'm meant to go on Saturday and am terrified - plus how many people use the weight check chairs?
Ok, I havent been to AT since 13 opened but here is my take on the rides you may encounter problems on.
Nemesis: Has 'big boy' seats designed for the larger guest. If you ask the ride oppos when you enter the station they will guide you to them, there are only one or two per train. Worst case is you try a normal seat which is fine if you fit but if you dont the oppos will either swap you with someone sitting in a big boy seat or hold you back for the next train.
Oblivion: Also has big boy seats but not on every train. If you ask the oppo who is batching (he/she is the one that asks you how many are in your party) they will get you in an appropriate seat.
Spinball Whizzer (sonic spinball I think its called now) You could struggle with this ride as it has a T shaped lap bar that has to be pushed in so many clicks before you are allowed to ride. I find that this bar pushes against my stomach. When you get on, cross your feet before you sit down and raise your arms before they push the lapbar down. The oppo told me to do this on my first ride and I have had no problems since.
The Flume, Rapids, Battle Gallions should all be ok.
Rita is tight but I always managed to get on. There are no bigboy seats on here either.
I havent had any problems at all with air but have seen a couple of people struggle to fit.
Many people seem to have problems fitting on submission and ripsaw but I have never tried. Coasters are my thing not flats.
Enterprise, duel and RMT should be ok. The lapbar on Hex can be very tight but I have not had any problems.
I have always found the oppos and staff at AT to be very good at getting me into the appropriate seats and while it doesnt bother me one bit, some people get embarrassed asking or when being held back for the next train.
Hope this helps!