It is all a toss up.
Our first experience at RBM-Richardson was positive but they didn't fit us right. I had a guy in the Frisco store tell me that the Richardson is known for not being that accessible and thorough. But then when I was in the Frisco store before they also seemed a little stuffy and not that friendly.
It all boils down to chemistry between you and the sales guy. My wife doesn't get as much respect as I do because she doesn't get obsessed about bikes...she just rides. I have seen it first hand. Then I have gotten the hurried service as well on occassion.
Here are my recommendations:
Plano Cycling: see Barry
RBM (Frisco): see Scott
Wheels in Motion on Coit in Richardson: see John
Scott was awesome when I was in RBM. He knew all the particulars. He told me that he would not let me just buy a bike without a fitting. He spent a lot of time with me just talking....but this was a Tues evening and it wasn't busy.
John at WiM was just crazy about bikes. He could tell you all the technology and history of a given frame. He practically begged me to try out a bike and went through great detail to be sure I was educated. He took me in the back while he set up a bike and even though other customers were needing help he kept working with me.

RBM richardson - same crap everytime. The people are nice but they are like WalMart. They have so many people in there that they usually don't have time for you unless you are a regular or have the "look". They wouldn't let me take a bike past the parking lot for a test ride....even though I had ID and they had my original bike since my wife and I rode to the store. I am ready to lay out 3k and I can't take the bike out of the parking lot. Screw that!!! I only go there out of necessity. It really is a crap shoot.