Mine has Hi-Fold doors 40X14. They fit up against the outside of the building on the gable end and take up no extra headroom. That is, you don't have to build the walls higher than needed just to provide headroom for the door because the hinge is above the door opening on the outside. You do have to double the gable truss and brace to the next truss back. (Hydraulic doors are great if you can afford them.)
They come as a frame and lift mechanism. You add the sheeting, lights or translucent panels and insulation to taste.
Desirable hangar features:
At least a 3'0" walk door (in side wall not in big door) or 4'0" if you can swing it.
Better lighting than you think you need
Windows on each wall for light and cross ventilation
Lights (by that I mean what you think of as a fixed window) in the big door
Lots of power outlets
Water (and all the amenities)
Heat (and maybe air conditioning)
Enough Room so you can roll a tool chest around the airplane
Note - if you use overhead radiant heat have a high enough sidewall so you don't cook your airplane - I think you need 8' or so but check this out on your own.