EPCOT and DHS are the only parks currently tiered, so correct.
Our experience using FP+ for shows varies. IllumiNations had a nice reserved area, but I would absolutely not give up a Soarin' or Test Track FP to get this. I only booked it because we were in that small window of opportunity before the tiered system started. My strategy for EPCOT will be to get Soarin' FP+ and ride single rider at Test Track. (except this time because someone will have to hold dad's hand for the area where you build your car at Test Track, so we got an FP for Soarin one day and Test Track the other day.) For IllumiNations, I'll just stake out a spot like usual or try to take advantage of some other package deal that comes with reserved viewing. We did the Undiscovered Future World tour and that had reserved IllumiNations viewing at that time. After the inclusion of IllumiNations with Candlelight Processional, I could see a Fantasmic! style dining package becoming a regular guest at EPCOT.
At Indiana Jones, we didn't understand how to use the FP, so we showed up at the end of the "arrival window" and we had normal, kind of crappy seats. By Festival of the Lion King, we had learned to arrive at the beginning of the window printed on the ticket and we had seats in the first full row. We're going to try a FP for Indiana Jones again and try arriving earlier. I don't need my other FP in that tier, so we're going to experiment and see if the experience is better if we arrive early.
Has anyone actually booked a FP for Wishes yet? I booked my FP+ for April on Tuesday and I didn't see that or Be Our Guest on the list of options for MK. I saw people using both in December. Does anyone know how to get them? Are they still in testing phase and by invite only?