Another one who goes solo at least once a year and have to admit I might enjoy it more than when I go with my son. I agree, maybe try to do all 4 parks, I've accidentally done it and it really wasn't all that hard, mind you that was before Pandora. What I did:
Got to AK at rope drop, didn't mean to was just up so thought what the heck. No FPs - rode Safari first thing then EE single rider then walked both trails, caught the bus to MK. No FPs, I think it was around 10 or so, rode BTM, COP, PeopleMover, POTC, HM, JC (not in that order), grabbed some fruit, caught the bus to HS. Maybe around 1 or so now, no FPs - rode ToT and grabbed a FP for TSMM while in line, rode GMR, got an ADR for HBD while in line for GMR, ate a late lunch early supper Cobb Salad and a wine flight, walked over to Epcot - this was during F&W, walked around WS and to TT, then to SSE, then walked through the Living Seas, over to Soarin and The Land (the Land at night is cool) and back to WS, grabbed some food from the booths. I was back at my resort (BW) by around 9. Notice not many FPs. I don't ride Space Mountain or RnRC or Dinosaur, they hurt my neck and don't normally ride TSMM when I'm by myself because it's not my favorite ride but it was there and so was I.
Now with Pandora I'm guessing I'd try for FPs for there then work around those. If not able to get FPs, I do that at rope drop.