The printer makes a difference, too. I had a couple pictures from my old 5mp Minolta PnS printed at about 17x22 or so. One was a straight-from-the-camera jpg, one was a mere 1280x1024 resize - and both look, imho, very, very nice. Certainly, the same pictures made from my current DSLR would be sharper, but even the 1280x1024 one looks quite good even upclose, just a little soft. The other looks fairly sharp. Both were bright daytime photos, so they were ideal conditions for the camera, which didn't hurt, either.
The printer was a very nice (it pains me to say this!) Canon one... of course, it should be, it was a $100,000 printer used at a Canon tech demo!
I would say that a good 6mp print from a quality source should be able to go at least that big without you being unhappy with it. If they're coming a DSLR, that will help even more. A "mere" 11x14 should be not much of a challenge at all for 6mp.