I open and conceal carry my Glock 23 and occasionally my Ruger P90 but not so often. My duty weapon is a Glock 22. I'm toying with the idea of getting a Glock 27 for a backup weapon when on duty as well.
I love my 21SF. I carry a 36 (or Ruger LCP) off duty - it's a little bulky for a thin guy like me, but it's not as bad as a 30.
The LCP is so comfortable to carry...I'm not a big fan of .380, though, and the trigger is terrible.
You can't really go wrong with a Glock (unless it doesn't fit your hand right, of course). There are other options, naturally - I haven't yet shot a Springfield XD, but I've heard really good things about them. It may be worth looking into.