Lori- It is so hard for me do pick the dining too! I love many on your list, and it is so hard to choose! You do get six TS credits.
In my opinion:
MK- We really like LTT for lunch- the items we got were very good, especially the desserts!

Ever since they got rid of the characters, I don't think the dinner is worth it.
Epcot= Just too dang hard to choose, I tell ya. We've gone to Coral Reef twice and really liked it. Granted, the food is good, but I've never been completely wowed by what I've gotten (DH disagrees- he still drools over the mahi-mahi he got last time). The atmosphere is what brings me back there because I love watching the fish tank!
Le Cellier is also good, but I liked it better when I went there years ago (2001). The last time we went in 2007, it was good, but I think it lost some us its luster- I didn't get what the worship was all about (JMO).
Garden Grill- Comfort food that is just okay, but we've gone often because DD LOVES Chip and Dale. Gotta take one for the team sometimes. And the rotating restaurant is really cool.
MGM- I see you made your choice, so you seem all set for that!
AK- We really like Tusker House for breakfast. Good buffet with the classic characters in safari gear. It forces us to get up early, which is good because We find that we like to get AK started and ended on the early side (it gets too hot and crowded in the afternoon!).
As for your extras- We had a really nice dinner at Kona, but that could have been the lapu lapus talking!

While it was good, I don't have the burning desire to have to go back next time, so we're trying Ohana next time instead. We're also trying Whispering Canyon Cafe next time as well because it looks like lots of fun! We're also going to try 1900 Park Fare for dinner (maybe next time or the trip after that) because DD loves Cinderella and those step-sisters are a HOOT! We ran into them in the MK on our trip before last and they were absolutely hysterical!
I'm probably no help here...

I always make and change my ADRs at least twice before every trip, and finally just settle for what I manage to get the best times for!