Your problem sounds somewhat similar to the problem I experienced.
Warped rotors can be a source of wheel vibration. A lot of things can cause wheel vibration, as well.
You may have bad tires. Your tires may be improperly balanced. You may have a worn out suspension component, like I ultimately had (worn out tie tod end).
I would recommend getting your tires balanced first by a Hunter GPS9700 balance machine. The website is located on the thread posted below.
Check it out. I think somewhere on page 2 is listed the many possible sources of wheel vibration:
Bad tires or bad wheel balance