I have attended the British GP this year on GA and here is my feedback on it for anyone interested for next year.
I couldn't go in Friday due to travel issues i only arrived in the UK on Friday evening.
On Saturday we walked around the track to see the decent spots which were at Vale, Becketts and Stowe, we tried the Farm and Village complex but couldn't get a decent view so we thought the 3 spots i mentioned were better.
At Vale you get very close to the action, the cars are slowing down heavily so you see them for quite a while, no chance for an overtake in F1 (maybe in other series) and there are 2 screens very close by for you to watch the live timing and tv when the cars are not near, very muddy.
Stowe is where you would see the most overtakes and wheel to wheel, but i couldn't see a screen nearby (or maybe there was but it was far away i don't remember), the action there was present in all series (GP2, GP3, Porsche and F1) so this is the were to be to watch the most overtakes IMO and it is usually crowded, very muddy.
Becketts is another story, you see the cars coming in at full throttle, take the Left-Right fast chicane then take a small right then to the very wide turn and the full throttle corner cut they do when entering the straight before stowe, all that can happen in front of you if you select the right spot (which i did

). There are 2 screens there so you can see the action but they are quite a distance away so you don't see the fine details such as driver names and times in the rolling tape at the end of the screen. In the wide turn right after Becketts is where you can expect the some overtakes in the lower series and the most accidents as well (the GP2 and GP3 races had A LOT of accidents there, i don't remember which is which but i recall 3 cars hitting each other). in F1 we also got to see the blown tire there as this was very close to where i stand, Romain getting off, and Di resta struggling. and the Webber vs Alonso battle was very good to see there.
We chose Becketts for the screens and mainly because we can see the cars doing so many things in there as you see nearly 5 turns + acceleration and braking.
Overall i would say it was an excellent weekend and we thoroughly enjoyed the experience there, the track facilities could have been better (bathrooms and such), the food was OK throughout, there was always something to do with the other partners and booths (LG had a very good place there and very entertaining playing the F1 game in the LG's open wheeled car cockpit). I would love to do it again in Silverstone or any other circuit.
What i would do differently, USE RAIN/MUD BOOTS, get a bigger umbrella (we were sliding all over the place), get a chair and some drinks before going (we didn't get chairs for all the 3 days, ended standing up the whole time or sitting on the gravel). GA is good but for next time i would select a grandstand, either Becketts or Stowe with as close to the screens as possible, its nice to have a roof over the head in Silverstone.
Renting
this could also be very handy when staying on track for the race and qualifying as you do miss out on a couple of things. it was 40 pounds to rent on race day which i thought was a bit expensive but it would have improved the quality for me so maybe i should have went for it.
For the say we were staying at a local bed and breakfast in Daventry which was very nice friendly ( the night in a twin room was for 65 pounds), but the problem was that since we are not from the UK we didn't expect that transportation would be THAT expensive but as there was 4 of us we ended up taking a taxi (there aren't many ways to choose from to go to Silverstone) to the track each day and dividing its cost but still that is a lot of money, my advice to anyone going RENT A CAR it would save you a ton and make transportation relatively easy if you have a decent GPS app even on your mobile. Daventry itself is very nice and quite, you can get everything that you need from there but the shops close pretty early (even Tesco) and there is a local club there, which i didn't enter, if anyone is interested (but i wouldn't recommend it, go to Northampton if you want to it would be better there )
I hope this helps.
Edit: added the stay details.