General admission will be fine, there is plenty of viewing areas, a nice terraced area after the first corner ( Copse ) and the walkway all round the track is good, there is a banked grassy area at Vale, and good standing areas in front of many of the grandstands, a personal favourite is to go onto the infield and stand in front of the grandstand at Aintree which leads to the Wellington straight as you can see quite a bit from there. Another good spot is the terraced area at Luffield. Take a radio ala TT if you have one, the main advantage of a grandstand seat is the shelter if it rains, but it's going to be lovely this weekend !! There is a free shuttle bus but it is usually quicker to walk, my advise is have a wander round as soon as you get there, then pick a spot for the racing. Pull off a map from the Silverstone web site it should show you the areas I've mentioned.
Finally, have a good day out, see you there.
Brian