ADRs are essential during
Free Dining. We've never been turned away from any Disney restaurant as long as we had some kind of ADR there.
I plan ADRs out based on what I expect us to be doing each day. I take the park hours schedule for my trip dates, then figure out which parks to plan on which days. You don't want to be traveling all over the place (especially if you're riding the buses) to use your TS credits. Fit into a schedule, they are a very enjoyable break from walking around in the heat.
If our flight is early (usually), we like to go to the World Showcase on arrival day. It's a nice low-key way to start park touring. The next day is always MK. Because of sentimental reasons, we always do the MK on our first full day. Our other MK day will be when the night time parade is playing or PM EMH. Studios day is when Fantasmic is playing. Love to do PM EMH at Epcot, so that's our Future World day. Animal Kingdom days can be interchanged with a day of rest at a resort so for either rest day or AK day, I pick a resort restaurant for an early dinner.
When going to the MK, these are the ADRs I might schedule:
Chef Mickey
Ohana
1900 Park Fare (only breakfast here for us--had a very bad dinner experience here)
Crystal Palace
Whispering Canyon Cafe
Choices are vast at Epcot. At Future World, you would want the Coral Reef or the Garden Grill (but GG only if you're a party of 4 or less--ugly view at the "big" tables). In the World Showcase, you could choose almost anywhere and have a great experience. We've enjoyed LeCellier, Chefs de France, San Angel Inn, and Biergarten on past trips, and I would recommend any of them.
We like the Cape May Clam Bake Buffet. It's good to schedule for AK, rest or Studios days. For Studio days, we've had great experiences at the SciFi Dine Inn and Mama Melrose. If you can get the Fantasmic package at MM, go for it.