The public grandstand seems quite well placed - I'm not sure, I haven't been seated there. Generally as close to the middle of the runway as you can get is good.
400mm is ideal, but you can get by with 200 - 300 with some thought. I looked at some exif data for some numbers, these are taken from the crowdline, normal fighter-sized target, about side-on (F-16 / F-18 / Tiffie)
On the runway: Approx 160-200mm
Southern taxiway (far side): Approx 200-280mm
Low-speed pass / high speed pass (these are usually right between the runway and far taxiway): Approx 250-300mm
Anything else, you're knackered, unless you've got a longer lens. The last two years, the Dutch F-16 has stood out as coming closest and slowest. The B-1 and B-52 will seem absolutely gargantuan after you've been looking at little fighters all day.
You'll enjoy it!
It takes a big man to admit they are wrong, and I am not a big man.