Decisions, decisions

Because train tickets are filling up unusually fast this summer for everything, we're forced to plan at least 2 weeks in advance for everything. With that said, we have a 4-day weekend after Laura's wedding. The big decision is whether to:
1. Original plan: Go to England (Harry Potter weekend). Unfortunately, the price is 100 pounds... which is a LOT of U.S. money for just the train ticket there and back.
2. Go to Spain. Tough to travel to/from and get reservations for, but possibly doable.
3. Prague or Austria (neither are on our itinerary)
3. Do a bunch of free stuff. Switzerland is going to be so expensive that I may need to save up on money for that (in two weekends -- look forward to pictures!)

Any opinions? I plan to go to Wimbledon at some point in my life (can't go that weekend; it's over by then). It'd be nice to go to London now, though, while a few friends (we'll see how many) are still planning to go and before I decide on whether international study would be any fun for a master's degree. Still... 100 pounds is probably the equivalent of canyon-jumping:

OR Zorbing