Richardson Bike Mart (the one actually in Richardson) is my bike shop of choice. I have purchased 4 bikes from them over the years, including my flagship Colnago C40 and my Specialized M2 StumpJumper Comp. great service all-around.
somebody mentioned a shop in Lewisville... that would be Bluebonnet. I bought my first real bike (a TREK 1000) from them years ago. the owner Ben is a really nice guy and you can't go wrong with them.
Plano Cycling is owned by 'Bikin' Mike Keel', he is a complete asshole and i refuse to even walk in the door of that place.
but if you're lookin' for cruiser or commuter bikes or whatever, Richardson Bike Mart has by far the best selection of bikes of every type.
JPdM