For family snaps etc I use Photoshop (CS5) to crop, improve (anti red eye etc). I keep on my PC copies at A4 size, 300dpi in case I want to print myself, but mostly I reload the ones I want on to a SD card and take them to ASDA - very cheap, ok for snaps. I do print some on a Canon MP640 using Canon ink and Staples paper , with good results. I am sure there are "quality" print houses on the net.
Hands-on: Acer Predator Triton 700 review