Cylinder & Slide is more on the order of someone to do true custom gunsmithing and custom alterations.
They're EXPENSIVE, and turn-around is slow.
Quality of work is sky-high.
For standard repairs I recommend:
The Colt factory.
NO ONE knows more about it then they do.
Price is very competitive, and turn-around is usually the fastest.
Pittsburgh Handgun Headquarters
1330 Center Ave.
Pittsburgh, PA 15229
(412) 766-6100
Pittsburgh used to be Colt's overflow for warranty repair work.
They apparently have a good supply of parts, and still work on the older guns, for which Colt doesn't have parts anymore.
Price is good, turn-around is good, and quality of work is factory-level.
These are the only places I will recommend, because I KNOW the quality of their work.