9mm has all of the "impact power" that you need. The fact that you train with it and are confident in yourself and the handgun itself trumps a larger caliber every time. Shot placement is the single most critical aspect of stopping a threat.
If you are talking nice CCW it is hard to beat a 1911. Both Springfield Armory and Kimber make quality compact 1911s in 9mm. I have owned both the Ultra Carry II Kimbers and the Ultra Compact Lightweight. CurrentlySpringfield is only making a 9mm in the EMP line which is nearly teh same as the Ultra Compact Lightweight but a little bit smaller.
If you want double action, I would look at the CZ or Taurus offerings. They both make compact reliabledouble actions.