I stayed at the Fiesta American last month, for the third straight year. It has always been clean and business in order. As someone earlier mentioned go ahead and get the AI plan for the drinks, breakfast, drinks, lunch (which are just okay), drinks, 2 included dinners at the Miramar for a week stay, and did I mention drinks! The cervezas are served in cans which they typically do not open (hint: Stock your room!). The staff is overall very friendly. A few bucks cash might just get them to leave a few cervezas in the cooler by the pool for self serve after pool bar closing hours or to open the bar for you an hour or so before 11:AM in the morning (like departure day). Anyway take care of the staff even if you are on the AI plan and they will go out of their way to make you smile. The daily entertainment is not too exciting, usually after diving and nap, we would make it to the pool bar for 2:30 bingo, followed by pool voleyball or a dart tournament, followed by Soccer or beach Volleyball around 3.
Go to town for dinner when not eating at the Miramar. Dinner at the Fiesta is pathetic IMHO! Use Christi's restaurant list. I highly recommend Especias and La Choza. Get to Especias around 7PM before the dinner rush and take some time to visit with Adrian. He has some great stories and won't mind sitting to visit until businness picks up somewhere around 8, not that anyone is watching the clock. Also if you ever considered learning to kite surf on cozumel this guy can set you up. If you don't see just want you want on the menu ask and he will deliver.
Have a great time!
Jeff