Coltishall would be top of my list. Loved the place.
Second place would be for Boscombe Down to be utilised more than it currently is. I know it's still open, but I'd love to fly FJs based out of there. Sadly I'm not TP material so it's unlikely!
I would vote to get rid of Coneheadsby. I think it's a bloody miserable place but I think it'll be around for a while yet!
BV