I felt the same way before our June 2010 trip, the first for DH & DD, my second (first one was in 1986, so this was new to me too!). We were there six night, six days (2 half days) & saw a lot, but we know we missed most of AK & half of EPCOT WS. DH had said this was our once in a lifetime trip, but by the time we left, he had promised DD that he would take her back someday!
I decided that DH & I would choose things that were most important to us, then just go with the flow. DH want to go to TL waterpark & stay at CR, MK view. I wanted to do character meals to avoid standing in line for autographs. DD was only five years old & had no clue. She just knew we were going to WDW!
I made our resort ressie as soon as the rates came out in August. I charted all ride height requirements, seating arrangements, ones with photos. I charted all meals by the characters & menus. I made ADR's the morning of 180 out, making the most important (to me) one's earlier in the week. I got all ADR's I wanted within 15 minutes of the times I requested! After that, I made the itenrary, working around where our ADR's were for each day.
We did always come back to the room after lunch for a few hours for a rest break. DD never did take a nap, but it was nice to cool off & rest. We would leave the room for our dinner ADR, then back to a park if the ADR wasn't in a park on that night. We were back to our room between 10 & 11 every night. I was up at 6 a.m. every morning. We kept our schedule pretty much as it was at home and everything worked out great!
I planned that trip for two years & had a huge three-ring binder full of notes & charts! I finally had to step away and realized that we couldn't do/see it all & that we just really needed to concentrate on having a good time doing what we could do.
None of us left WDW disappointed. Next time, we'll spend more time at AK & EPCOT. We spent most of our last trip at MK since we stayed at CR, so close. If you need to leave out some places, I'd leave out DTD & waterparks.
Just plan away, but don't plan it down to the minute---I planned ADR's, then the rest of the time was free for whatever shows/rides we wanted to do.