Most of the "home use" 4 Post lifts do not need to be bolted down, per manufacturer's instructions. That being said, I believe all of them have mounting holes for bolting them down if you want to.
In a professional shop environment, especially if you have employees, the ALI Standard requires the lift to be bolted down in accordance with the manufacturer's instructions. (OSHA would have a cow if they saw a lift that wasn't bolted down!)
If you decide not to bolt it down (home use)try to make sure that the floor is relatively level in the area that you want to use it. The floor should also be free of cracks.
The Rotary Revolution Lift (
http://standardus.com/stdshop/rotar...s.-capacity-enthusiast-revolution-r-rfp9.html ) ships with a caster kit for rolling the lift around, as well as drip trays and a jack tray. The BendPak lifts have them as available options at additional cost. The Tuxedo lift line also has the caster kits included, but the drip trays are additional.
Good luck with your lift purchase!