I went with some mates in 2010…
I found the best GA at the entry to the second chicane if you can get there early enough. There’s always good action there, and the crowd keep a fun, almost footy like atmosphere with their chanting and the like.
Alternative spots include the exit to the Ascari chicane, and a must is to experience the sound as they go under the banking just before Ascari. It’s like no other, even the sound under the freeways in singapore doesn’t compare.
As you’re walking around the track, be mindful of the thorny shrubs. Otherwise, have a ball and enjoy the atmosphere! It can’t really be beaten!