variety is the spice of life
try for at least 6 different themed fields any with structures provide a gantry for Refs and see if you can install some sort of lighting on some for night games.
make at least one speed ball field (possibly 2 or 3 differant types)
a "village"
a "fort"
and a large woods field (combine the three and make a huge scenario field)
depends on budget and the owner of the land but if you stick with a few "hay bale" style fields it'll be boring after a while.
one speed ball field at Marchbrook Wrexham(Wales) near England
is called Buffy's play pen, its a grave yard (using flag stones as graves) lit with fluorescent strip lights and with clouds of CO2 its fantastic at night.
One thing a lot of sites do is call fields after major battles, I would do the names differently like the graveyard one above.
And when its ready to open tell me when and I'll try and pop over to have a look