I went with a BendPac HD-9, 4 post drive on lift and 'rolling jack'. It works great for everything so far... but rotating tires takes a bit longer this way! I still use a floor jack outside if I'm just going front to back on the same side of the car for tire rotations. Speaking of floor jacks I like the American Forge and Foundry... which is made in china unfortunately...
http://www.asedeals.com/automotive_floor_jacks.html model 200T
My garage is 24 wide by 28 deep... with a 101" ceiling.


The runways are just about the same height as the scissor lift, and the rolling jack sticks above the the runways by the same amount. On most cars this isn't a problem but on my firebird the UE torque arm chassis mount and exhaust hang pretty low in the middle so I have to drive one end of the car up on 2x6 blocks first.
I prefer a 4 post for a few reasons:
-no posts get in the way when opening our humongous doors
-no need to really worry about your floor being thick enough (mine isn't even bolted down yet)
-you can store the car in the air without hanging the suspension and with drip pans you can park another car under it for the winter (assuming you have the ceiling height)
-it's the only way to do subframe connectors
-the runways make a good alternate to a cart for tools and parts
-the runways also don't really get in the way, if you're doing suspension work odds are the car is up off the runways anyway
-you don't have to worry about the center of gravity getting out of whack when pulling a motor
-no bending over to make sure you're on the lift right... call me lazy
But there are some down sides:
-4 posts instead of 2 to get in the way, and asymmetric lifts don't always block the doors
-you still have to get the car somewhat centered when parking on it especially if you're going to use the rolling jack
-to do front springs on a non-coil over suspension I hung the front of the car off the lift and put wood blocks under the lifting points of the car. I kept the height at the average for jack stands so I could use a floor jack under the ball joints.