... with 2 meg ram.
well there's your problem.
seriously though, if you have the extra hard drive space, shoot 1080. you can always cut it down later if you like. and as for it ending up on youtube, youtube now streams 1080p videos. the number of ways people have to view youtube vids on their hdtv's is growing every day as well.
as for the editing question, you edit using a preview, and render the video in full resolution at the end, so it's not like you're trying to render the full hd image as you're making changes. granted the rendering takes some time, but you don't have to tend it. my particular machine renders 720p video at about 1/4 speed, so 1 minute of video would take 4 minutes to render. it's a 2.4ghz dual core/2gb ram system which is several years old.
ok, so i may not be typical, but i sometimes watch kite videos i've downloaded streamed over my network to my hdtv, and the more pixels the better in my book.
personally, i'd rather have the higher resolution than the higher frame rate. if you were talking 15 vs 30fps i'd rather have the fps, but since you're talking 30 vs 60, i'd rather have the resolution.