I have been hoping to go to a F1 race for years now, but my problems boil down to money and finding at least 1 other person interested in going / spending money! I have 3 choices in mind though.
Britain of course is one, being our home race. Can travel up on day, get caught in loads of traffic, watch an Ok race (Silverstone is usually one more for the tacticians rather than the spectacle...), then get caught in more traffic. Its the cheapest but you still pay a heck of a lot just for Sunday tickets.
Next is Belgium which many others have said due to the magic of the circuit. Its slightly more expensive than going to Silverstone would be, but we'd get a road trip from the event if we stopped by other places as well. One friend who is interested though isn't too happy with the road trip aspect or likelihood of rain...
Finally then, Abu Dhabi. Most expensive by a margin, but we are thinking it would be more about the holiday than just the race. Ferrari world to visit at the circuit and Abu Dhabi itself sounds like an amazing place to spend a week or 2. Race itself can be a bore as well though, but potentially the crowning place for Vett-the 2012 champion. Plus as a final bonus, friend has discount on long haul flights with Virgin!
That's how far planning has got so far, and I think money will be ultimate factor for others. Another to throw into the mix though is Hungary, since the tickets for the weekend are amongst the cheapest and you can still make a holiday of a F1 race weekend visit.