Yeah I thought 16GB would be enough last time around, but whenever I was travelling (even train journeys in the UK) I would find that it just wasn't enough, what with having some music, movies, podcasts, photos and beefy games on it.
I'm going on two long haul holidays this summer too so going to want the extra storage space for the flights alone!
Queued for 9 hours from 7am?! Geez. I went down to the Liverpool ONE store for iPhone 4 launch, got there at about 4:30am and was about 25th in the que or something like that. In front of me were a couple of guys who had flown over from Amsterdam for the day just to get an iPhone 4.
For iPad 2, I'll be heading down there before that I think a) so I definitely get one, and b) as I have to get a train asap that day, so the longer I leave it, the longer I'll have to que up. At the moment I'm thinking around 3am.