I like the idea of having separate flight lines. If I had my choice of any configuration, I would have the pits in the middle, with the runway on one side and the helis flying on the opposite side of the pits.
In the pit area, some shade trees would be nice so that folks don't have to bake in the sun all day. Also some descent restroom facilities. And if you are going all out, maybe a hotdog stand or at least some vending machines.
As mentioned already, some good work benches.
An engine break-in area away from the pits.
Russ.