Full - my only fulls so far have been at WDW and it's difficult to imagine a better run environment in terms of what to see, flatness, and temperature.
Plus I haven't traveled to do any other >10K races. The MCM this fall will be my first out of town distance race; I'm hoping it is also a new favorite.
Halfs - Disney, plus a few halfs here in Atlanta. One of them here in the Atl took us from Olympic park out past the MLK jr crypt (cool to finally see that), back through mid-town, through Georgia Tech, and back to Olympic park. That was cool. I even had motorcycle escort near the end. For about 20 seconds, then the full marathon winners came blowing past me....
10K - It is hard to beat the Peachtree Road Race with 60,000 of your closest friends. It is a 6.5 mile long party through Atlanta. With the cheering crowds and the music (both recorded and live) the whole way, plus the need to hear other runners around me, I don't even bother with bringing my own music.
That said, the PITA factor and the added fees for mailing (i.e. the penalty payment for not going down to the expo) mean that I'll skip it this year. Something literally doesn't add up with the fees charged on top of the cost of the race.
My bucket list for out of town races:
USAF marathon (especially since I'm an aerospace engineer)
Indy - didn't even know about it until reading this thread. Finally made it to my first Indy 500 a few years ago.
NYC marathon - just to do it once
And maybe some others gleaned from this thread.