Switching tables once in a while can't hurt, unless you're making a killing at the table of course! Who'd turn thier back on that?!

But one thing to consider is cold runs of cards.. If you play a tight game, and the cards are just stone cold, you need to do either one of two things:

Change tables,

or start raising the odd crap hand from early to mid position to see the response you get.

Just yesterday I had a cold run of cards and before I had realised just how cold it had been (two or three orbits I think it was), along came the money hands.. Now, say what you will about 10NL players, but the ones at this table had happened to notice that the "rock" had raised.. And, surprise surprise, my nice shiney aces picked up the blinds. Twice. In Three hands. I was less than pleased.

Anyway, the lesson here I guess, is to pay attention to your cold runs and make sure they don't affect your profits.

Bleh so long question made short.. "Should I change tables frequently!? and should I avoid tables with people I know play decently good?"
You'll likely always have some known decent players at just about any table you sit at, you just have to give a little respect where it is due, is all. On the upside, you have to advantage of already knowing a little bit about how these opponents play..

s.