I have used SmugMug for photo sharing, one of the perks of sharing images with there site is the photo printing. I have always been impressed with their quality and shipping speed. Their prints might cost a bit more, but it seems to be worth it.
I have also had prints made from Shutteryfly, Walmart, Walgreens. I normally use Walmart for when I need one hour prints done. The quality just doesn't seem to compare.
I would also suggest making a Blurb/Shutterfly book. Either site has an easy way to create a book, which is a lot more interesting for people then prints.