Are you on the dining plan?
MGM is lacking in the "better" TS situations. You might consider taking a break out of the parks for a good TS at one of the boardwalk resorts or at Epcot if you have a PH. As far as CS, Pizza Planet is ok, and you could easily split a pizza/salad combo. If on the dining plan, we liked ABC Commisary better, the fish and chips were good, it seems pretty quiet and is indoor a/c seating. I haven't been to Backlot Express, but it seems to get better reviews than ABC.
AK, Tusker House gets far better reviews than the other CS's there. They will be opening a TS restaurant there, asian inspired, I think in the early summer, if I remember correctly. The only TS there is Rainforest Cafe. This is a park that I would consider doing a TS at a resort or again, in Epcot if you have a PH. The park closes earlier than the others, at 5 or 6 most nights, so it is easy to wait till after visiting the park to eat TS.
Have you checked out the menus at allearsnet.com yet? That may be the best place to start, then start a thread on the restaurant you think you might want to visit for some first hand experiences.