Learn about the Fast Passes and use them! When I heard about them, I thought they were a hassle to set up, trying to figure out which rides I wanted to go on each day, etc. But once it's set up, it's so great. For example, do you want to wait 2 hr to ride on Space Mountain or 10 min? And once you've used the fast passes that you set up in advance, you can go to a kiosk at the park and get additional fast passes.
Also, get the app for your smart phone. It gives you live wait times for rides. If you are in the park saying, hmm, what next? You can pull out the app and see what has the shortest wait times and go right to those rides.
I've heard of people going and only getting in 5 or 6 rides in a day because they spent so much time waiting in lines. We rode a TON of rides by maximizing fast passes and the app. My kids like the roller coasters, and in 2 days in Magic Kingdom, we rode every single ride in the park once, and we rode the Mine Train twice, Space Mountain 3 times, and Big Thunder Mountain 3 times! And that is with spending a few hours at the pool at the hotel to cool down every afternoon!
According to my family, Test Track at Epcot was in the top 3 of the rides, along with the 7 Dwarfs Mine Train. They loved it. However, I get motion sickness very easily, so I did not ride Test Track and don't have 1st hand knowledge (I too loved the Mine Train). I personally loved Soarin at Epcot, which you definitely need to use a fast pass to get on, or you may wait for hours.
Have fun!
ETA: Also, when you are planning what to do on which day, look for special hours. Some parks will open early on certain days ONLY for people staying at one of the Disney resort hotels. If you don't mind getting up early and being there when the park opens, you can go to the park during the extra hour in the morning and ride on almost anything with a short line. There were some rides we literally just walked on to during that hour.
(Note: we went the 1st week of Nov 2015, and since we only had 3 days, we only went to Magic Kingdom (2 days) and Epcot (1 day))