I've been reading through all of the comments and posts and have learned a lot. Thanks for all of the great advice! I own a Canon T2i and the following lenses:
Tamron SP 17-50mm f/2.8
Tamron 70-200mm f/2.8 AF Di SP (no VC)
Tamron 18-270mm f3.5-6.3 DI II VC PZD (which I think is a great all around lens. I have used it on vacations with great results)
I have Hoya UV filters on all of my lenses.
I like to shoot concerts, mostly in small rooms, anywhere from 100-300 people. I can be anywhere from three feet from the performers up to fifty feet (that's where the 70-200mm comes in with a table tripod). I cannot use flash in these situations, so I've shot with both the auto no flash and the TV setting with the two f/2.8 lenses above. My pictures do not come out clear. The faces seem to be very white with no detail, and since the performers move around a lot, many of the photos are blurred. I have not yet tried the AI SERVO setting or the center-weighted average metering. What about the white balance? The lighting is anything from strobes to colors to dim spots.
Also, I'm thinking of purchasing a faster lens, such as the Canon 85mm f/1.8 or the Canon 50mm f/1.4 (can't afford the big telephoto Canon with IS). Do you have any suggestions for another lens and do you have any other camera settings suggestions to get clearer and better quality photos?