I've been using my new garage for almost two years now, and thought I'd give an update, along with some lessons learned that might be useful for others building similar projects. Overall, the shop has been great, but there are a few things I'd do differently.
To recap: the garage is 24' wide by 34' deep, with an 8'x18' bump out in the back for air compressor/blast cabinet/storage, and a 14' ceiling height below the trusses. The place had to be built on a fairly tight footprint with limited access, which mandated the long/skinny vs wide/shallow configuration, with the roll up door on the skinny side, and the size was limited to 1000 sq ft by my local jurisdiction. In addition, since I had specified a 12x12 door in the the 24' skinny side, the structure on either side had to be pretty beefy for structural/wind shear reasons, so I have 6' tall reinforced concrete columns on either side of the door, one of which has a man door it.
Lesson Learned #1: Think hard about how many doors you need. I never use the man door next to the main door. And, because it was on the skinny side next to the 12' overhead door, it required the expensive reinforced concrete columns on that wall. An expensive mistake.
For equipment, I started out with a Bend Pak scissor lift on the left side of the space, and it has proved to be a terrific piece. I store my current fleet of cars, a 1985 911, a 1989 BMW 325i, and a 2002 Porsche Boxster S, in the space, which I can do by putting one car on the scissor lift and parking the other two nose to tail. There is still a nice amount of room to work on the side with the single car. Unfortunately, ingress and egress is limited to the hind-most car, because the centrally-located garage door acts as a bottleneck. Since I try to drive all my cars regularly, this configuration requires moving a couple of cars to access anything other than the one closest to the door.
Lesson Learned #2: Think hard about auto ingress and egress. The law of cascading effects is immutable. So a bad decision on the man door had the follow-on effect of limiting the width of the roll up door, which in turn limited ingress and egress. Without the man-door, I could have used a larger roll up door (say 16' wide instead of 12'), which would have given enough maneuverability room to get the car on the scissor lift out past the car parked closest to the overhead door.

Since my decisions on the doors are literally cast in concrete, another solution is required to alleviate the ingress/egress problem. I originally planned on installing a two-post lift where the Bend Pak currently sits, but my experience so far makes me nervous about its placement. So, after a great deal of thought, I've decided that the solution is a free-standing four-post lift on the side where I currently park two cars, allowing one to be stored underneath. That will allow me to pull out either of the two cars on the ground. After researching the current crop of lift out there, I settled on an Advantage DX9000HD. I previously owned a Backyard Buddy Classic (7,000lbs capacity), and really liked it, but it stayed behind on a move. BB has been purchased by Advantage Lifts, and though BBs like the one I used to own are still available, there is a fair amount of overlap between the BB and Advantage lines. I went with the slightly more expensive Advantage because of the greater 9,000 lbs capacity and the fact that once freight is factored in, the prices are a push; Advantage has a warehouse near me, whereas a BB would have had to be shipped from Ohio at a cost of over $800. So, advantage Advantage. It will go where the 911 sits in the photos.
So, that's about where thing stand. I don't want to give the idea that I'm unhappy with the garage--it's been great, and most decisions I made worked out well. The 6" slab is uncracked, the floor has held up well (though the scissor lift has ground some of it off), the drainage is great with the complicated gutter system, lighting and skylights make it a great place to work, and I've done a bunch of projects in there, as well as regular maintenance and repairs to my aging fleet. Next big thing is a 2.9-liter stroker engine for the E30. I'll update once the Advantage lift goes in.