The first thing to do is find out what you are legally allowed to do. Find this out from the AHJ (Authority Having Jurisdiction) which will be your town or county building department. All sorts of people will tell you all sorts of things, but you have to talk to the people who actually make and enforce the rules.
Next, I would play around with a free drawing software like SketchUp, and actually make sketches of the various vehicles you want to park and/or work on. Or, you can go old-school and simply work it all out with graph paper. In the old days, I'd make paper cut-outs to scale, and move them around on a proposed floorplan to see how it all fits. Make sure that there's enough room around vehicles to open the doors. Too many garages aren't wide enough to be practical.
Pole barns are supposed to be a lot cheaper, but by the time you modify it hang insulation and interior sheathing, the cost difference tends to fade. A metal building will get you in the dry the fastest, and can be pretty cheap, but they are ugly, and have their own challenges finishing the inside. Personally, I like to build on a slab, with all of the structure above grade. My barn is stick built, and the only thing I would have done different would have been to run a couple courses of block, then built on top of that. That makes it a lot easier to avoid rot and termites.
As for resale, you have to look around your area and see what your target audience might be. Do other houses have big shops? Out in the country where I am, a big outbuilding is a major asset. In town, a lot of buyers might be turned off, limiting your market. The appearance of the building is a factor, too. In more upscale areas, an attractive traditional barn will be more popular than an industrial-looking metal building. I built a very traditional gambrel roof barn, and everyone comments on how good it looks. My wife and I have to look at it, too, so it's nice to have a good-looking building.