With every photo session I have, I alway try to educate and ask the clients to seek out reputable printing/developing. Accessibility is amazing these days and we can get quality and FAST prints early anywhere. However, just because you CAN get them anywhere, doens't mean you should.
One blogger did an EXCELLENT POST with great visual examples on the different types of quality you might get back from the different developers. I'd start with this article before you just pick any old developer.
My favorite EASY high quality developer is Mpix. The prices are fair, delivery quick and quality is very good. I've actually never been disappointed. Mpix is actually an offshoot of Miller's Lab (as referenced in the above post) it is just now more consumer friendly and less geared only to pros.
However, when you download the images and I give you "rights to print" you may print those wherever you choose. This year, as I revamped my contract, I made sure to point out where I recommend you to print. Meaning I do not support Walgreens, Wal-Mart, Target and even Shutterfly being your printing options for the HIGHEST quality image. I put a lot of time into editing, color correcting and making sure your images match my artistic vision. Printing at some place less than PRO jeopardizes the end result of your images. As a photographer, I want your images to be the very best. I've built my business around saving the client money by NOT having you order prints through me at an exaggerated rate. Instead, I ask that you choose a high-quality developer.
Other developers I've had great success with are: WHCC, Nation's Lab and Miller's. For canvas I've had great luck with CG Pro and again MPix. For albums, you can also use Mpix or I strongly recommend Artifact Uprising.
As always, I'm happy to help and will always try to do my best to ensure that you are ALWAYS happy and satisfied with your images!