Clean, dry and safe staging area next to the playing field,
Lots of bins! imo i don't think enough places recycle the box's, I'v been to afew sites where they just burn everything at the end of the day
Chrono area which has alot of light going to it so you can adjust your marker clearly.
Flat surfaces on the playing field, regular cutting, clearing of old balls from weeks previoulsy.
Clean barricades! I really don't like the look of those indoor ones
been abit picky, but i'v seen some really dirty bunkers from pics that just look revolting.
Decent barricades, don't get ones which deflate after an hours worth of play, and also no bumps in them from over-inflation.
A training field for snap and domination drills as well as a couple of normal 5man fields.
Food canteen with somewhere to sit and eat thats dry, burgers, snacks, pre-prepared food.
Netting - Don't go insane with netting like they have for punters, just enough for the fields, its expensive. keep it nice and simple.
Site with easy access! Now I don't have a car, so I have a really hard time trying to get to alot of fields, if you get a site with a regular bus that runs late, or about 25mins walk from a train station with a good walking surface for your rollers then that would be fantastic.
Signs! Parking signs, chrono station signs, staging area signs, where the loos are signs! just simple post in the ground will do, make the site as easy to use for new comers.
Yes as bizy43 said, you do need fill stations, try and put the compressor away from where people are kitting up, and lead a pipe/hose to where the fill station will be. 1 3000PSI hose and 2 4500PSI hoses would be good.
TBH there are afew fields around, check out how those fields are doing and if another field is really needed. I hear of alot of fields closing down because of lack of people who are intrested in playing weekly, or even regularly, meaning that ballers area at a premium, get alot of intrest first, and keep your field lived in by ballers, have a campsite, sat night entertainment, get an atmosphere going to keep people coming back and a community going.
Things that I'd love to see at playing sites.