Wow! Great information from everyone. I really appreciate all of it.
Believe me, if I had my way I would build a 20,000 sq ft shop with 20' ceilings and a 500 sq ft attached house. 1500 sq ft is about as big as I can go, mainly because of San Diego county rules governing such things. For the size of my house (2900) and lot (3 acres), I can build a total of 2000 sq ft - period. Not to mention - $$$$. This is California, things are very expensive. I have land in Texas and could build a house AND same shop there for less than just this shop is going to cost. Also, once the shop is done, a new round of saving will start to build a Saloon (I live in a horse community/daughter has a horse/etc) so a Saloon will fit. Besides, one of my neighbors/guys I hang with for races and football games has a Saloon at his pad and....well.......I want one! So, I gotta save some reserve space!
The good thing is that the house has a 900 sq ft attached 'civilian garage', and I have a decent size storage shed for yard stuff. So with all of that, this shop will be MINE. Every single square inch will be items related to wrenching. I don't do woodwork (no talent), so no need for any of those types of tools/machines.
I spent hours and hours debating doors with a lot of my contractor buddies, Garagejournal research, friends who build hot rods, etc. At the end of the day, one roll-up makes the most sense for me. I will always have a project going (which will be measured in years), and the '88 which I drive. Hell, right now the '88 occupies the 'civilian garage' (well, shares it with the Harley and the weight racks, rower, etc). Wife parks her car outside so the K5 can be inside! That's love right there.........she loves that thing as much as I do.
I might go with 20' over 18', I'll see what the builder says (I get some serious wind and it will hit that door with full frontal force).
Toilet and deep sink (two separate plumbing fixtures) are in the plans already. I am still researching how to do the compressor/air lines. I am putting a 4' wide walkway on the 3 'back' sides of the building, with a 6' walkway along the front. I don't know if I want to use part of that walkway for a compressor enclosure, or build an enclosure over the bathroom.......still researching pros/cons. Hell, since I only have a little 'fill up tires' pancake compressor at the moment, I have time.
I really appreciate all of the great input, keep it coming. I'm still sifting through all of it, kicking it around, etc.