I was in a big complex with the old GE RR-7 system pretty much everywhere. It was really fairly reliable once they redesigned the switches so they would not bind on the cover but if they do stick, you burn out the relay coils. Other than that is is a very flexible way to do things since you are just running bell wire and you can quickly redesignate which switch does what.
I have worked with most of the Lutron systems, and they are all fairly good once you know each's limitations.
You need to decide if you want central "dimming racks" or local dimming.
Check out the Radio Ra 2 system, very powerful and flexible. The new homeworks is great too, but unless you are certified in it, you will have to farm part of the job out. It really depends how much automation you want. If you don't need IF...THEN control logic and massive integration with other systems, Radio Ra 2 is probably fine, as long as you have under 200 zones. It includes the ability to interface with other systems, add timeclock events, etc.
I am in your area, if you would like more info and possibly help designing this, please contact me privately,