good call with Spa, its a great weekend.
i've not been to hungary but i've heard good things about the views.
the general entry area around the back of the circuit apparently does allow you to see quite a bit of the track
i'd also consider Silverstone. granted its not that cheap, but if you have a grandstand ticket(any grandstand as far as i know), then you can sit in any grandstand you want on friday and saturday.
in 2010 we had tickets for stowe but watched free practice from the start/finish straight and qualifying from becketts.
so when you factor that in, its actually not bad value.