Paris
The nature of the trip changed dramatically in Paris for me. Everyone I'd been with until then had split, and I met up with Em, Calvin, and Jess. I had nowhere to go (no trains! incredible!) for a week, I didn't have to pay for a hotel, a cute girl was with me all the time, I had to deal with a group of people that had been together for more than a month and who were more than a little sick of each other, etc. Paris was great but I don't think I'd spend a week there again. Or at least I would know what I was getting myself into.