If you can swing it, I HIGHLY recommend heated floors. They're not cheap, but they're worth every penny. Now is the time, you can't do it after the cement is poured. We have a hot water heated floor in our basement, garage and shop and love it. You can open the big door in our shop for 5 minutes, close the door and 2 minutes later it's warmed back up, since the entire slab is warm. The other benefit is that the floor dries much quicker, and the heat is even from floor to ceiling. We have ceiling fans w/ remotes and they show the temp at the fan, and it's always within 5* of the temp down at the thermostat 10' below it.
Also, you are planning on having a drain in the floor, right?
Any other questions, be sure to throw them up. A number of us have built shops, so we can give advice and insight.
Sucks to hear bud. At least you have a dry place to work and park the truck at night till you can pour the slab.
Check on CL and newspaper ads for a boiler for your floor heat. Plumber in our town happened to have a perfect one for our shop that he ripped out of a house. Cost us well under half of what a new water-heater or boiler would've cost, and it still runs perfect after 4 winters.