The Central Parking System garage is the that I use most when I am in downtown Baltimore. It is relatively inexpensive when compared to the other garages in downtown Baltimore, however, it's not the best garage that is out there. If you are not looking to spend a lot of money, and don't really care about customer service, then this isn't a bad place to go.
The garage I park in is always clean and well lit. The elevators always work and I feel safe being there. However, they are somewhat lacking in customer service. I once called them to complain about a rude attendant and no one returned my call. However I'd still recommend them for the reasons given above.
Very convenient place to park. There are entrances on Market Place and Lombard Street. The closest parking to Power Plant Live clubs and bars. They even have security. Price is reasonable for the area.
Pros: lots of spaces, security, Friendly staff
Cons: Lombard traffic