This is a fun thread-- and a good opportunity for me to do something I never did when I got back from my September 2001-- thank the DIS for all the help! If it hadn't been for all the advice I received here, I would certainly have lots of regrets! Here's the big decisions I made that I DON'T regret--
1) GOING! We went 12 days after 9/11. We nearly cancelled- probably would have if we hadn't been renting DVC-- but finally went. We were so glad we did. The trip probably had a weird melancholy tone it would never have had before, but it also was sort of poignant, too-- leaving NYC for a week to regroup with our little family of three felt that much more special.
On a more superficial note, we were completely spoiled by the lack of crowds, and lines-- and we got there before the cutbacks (except E-night-- that was cancelled but we didn't need it.)
2) Taking it easy. It would have been so easy to do the commando route, but we just didn't-- I bought our park hoppers and decided to not obsess over how many hours in a day I was getting out of them-- if we felt like leaving a park at 2pm and spending the rest of the day by the pool, fine! And we did. We didn't obsess over seeing everything. Maybe not cost-effective, but more relaxing.
Of course, #2 leads to my few regrets-- well, not regrets, but wishes for next time-- there were a lot of attractions I missed that I'd hoped to see/ride. And we really never "got" Epcot-- we just never spent enough time there, and it always felt rushed. The only other "regret" is not spending enough time-- we did six nights-- which given that we decided on the vacation six months before, and started saving then-- was about all we could afford. But I hope next time to do about eight nights.