I really appreciate the advice you guys have shared. Some great ideas!
I am not in the market for a barn currently but I would seriously look at airplane hanger doors on one end. A friend lives on a private airstrip and it makes maneuvering so much better, and you don't have issues when there's a dead truck, boat, trailer in the way. He drives in and out with his plane and doesn't have to move anything! You could utilize storage above the opening for compressor, lounge or make it a mezzanine and store off season toys. Some of these options are possible with overhead doors too, but to take advantage of all the floor space you will eventually want more doors! They are basically folding walls, so they have insulation value and smaller service doors are an option in them as well.
I also recommend big shelving, on at least one side. Nothing worse then mowers, gas cans, sleds, chainsaw totes, fishing poles, etc cluttering up the space. At least 4 feet deep, and if done right sleds, ATV's can be parked underneath.
I realize that it may not work out but I figured I would mention it so you have another thing to think about