when I built my shop 32x60 I poured the slab extra thick where I planed on putting the lift. I have 12'6" walls and the truss's are 15' tall in the center. worked prefect as the 12K lift was just under 15' tall after installation. I have one bay dedicated to the lift. My problem is where to store all the stuff, welders, plasma cutter engine hoist engine stands, ect. ect. being a retired auto mech I have tons of tools to store. used to park my daily drivers in the shop until my wife started putting her shi... in there, and the daughters crap.I think I need another shop built only twice as big. just remember build to build it twice as big as you think you need :,
What Steve said on shop size. No matter how big though, I suspect it'll be too small a few years later.
And like Steve I had the same problem of family thinking my shop was the family, free storage facility. Then one day I decided I needed the shop back. Told everyone they needed to move their things out, I needed it out within the next month. Gave weekly updates on what was left. Then a month later on a cold rainy day I cranked the backhoe and dug a long, wide 6' deep pit behind the shop. As it got dark I started the fire and popped a cold one. Had a totally enjoyable evening feeding a big fire till around midnight.
Hard to believe but that was 15 years ago and only auto stuff in the shop today.

RonR