At 29-33 weeks I took my kids at the group home I work at to Busch Gardens. I walked all around, stayed hydrated and rested often (when they were on rides). My last pregnancy I had a preemie, but I am not on any restrictions this pregnancy and am doing well. I would maybe go for short walks every night just to make sure you are not doing anything your not use to at theme parks. As long as your not on any restrictions from your doctor you should be fine.
Re: Theme Park at 31wks, am I crazy?