Our 1st tier FP for Epcot is Frozen Ever After, and our 2nd tier is Spaceship Earth. There is no other 2nd tier ride that we really want to do.
You may need to pick and use a 3rd FP before you can get a day-of FP at another park. I don't know if that's true but it's worth looking into. So you're allowed 3 a day, but only at one park - if you leave that park only having used two, does the system lock you into that parking because it's waiting for a FP from there? We used to booked 3 FP at one park (usually HS) and then using day of FPs at the other parks as we go.