As a guide on the Yellowstone and Madison rivers in Montana I will give you a few tips. Others will give valuable advice as well, I know I will leave a good bit out.
If you are going to be fishing local water ask at the fly shop that you frequent for a reference. As you mentioned, ask someone you know and trust who they went with and if they would go with that guide again.
Look at some web sites. The web site can give you a clue as to the guide’s experience (I will go over this shortly), their basic fly fishing philosophy and the waters they guide on. However, I know some great guides that have lousy web sites ( and many who do not have one at all) and some less than great guides with a good looking web site.
Try to talk to the actual guide if at all possible. Many places in Montana have a core group of guides and you may not have any idea who you will be fishing with until the big day comes. This is just how things are run here. Many shops will have a short bio on their main guides, ask who you will be fishing with and check out their bio. Having said that, the vast majority of trips in Montana are arranged with the guide and client never speaking until the day they fish together.
A guide with many years experience often is a good indicator that you will be with a great guide who is patient, knowlegable and will go over the top for you. However, there are many guides who have been doing this for so long that they just do not care any more. The bottom line is, many years experience most likely is a good thing, however, there are many guides just getting started that will work their butts off for you. This is an extremely competitive business, so most guides and just about every outfitter will do their best for you.
If you are going on that dream trip then put on some coffee and sit down at the computer and do some research. Make some calls to the outfitters and lodges and go to boards like this and ask some questions.
The bottom line is that the vast majority of the guides I know love what they do and work very hard for their fishermen. Those that do not get weeded out very quickly. If you have a bad experience with a guide that is truly at fault then by all means talk to their boss. If they are self employed then talk to everyone you know about the bad experience.
One more thing. When you go on a guided trip make sure that you have realistic expectations about the water, the fishing and what a guide can and can not do. Most of all, know what your skill level is and do not expect miracles. Keep an open mind when the guide suggests a different fly, or a tweak to your cast. Go into the trip expecting to learn. That way, even if the fishing is no good you will still come out with a valuable day on the water.
BTW, I am also from Pa. For many years Penns was my home stream and I am looking forward to fishing there over Christmas.