Printique.com always does a great job they are owned by Adorama I've ordered a lot of metal prints from them not cheap but very high quality. I also use millers on occasion for larger prints and wall art but you need to get set up as a...
BayPhoto, MPix, Nations Photo Lab, Printique all good. Used to get a discount code when you open a new account, don't know if they still do. Most will drop ship in plain packaging so you don't have to ship it yourself. I'd suggest getting...
If it's just prints, try Walgreens.com with 1 hour local pickup. There are often online discount. Most importantly, you need to start with really great high quality image files. I'm fortunate to have a Walgreen's only 1 mile away.
It depends on what print media and level of quality that you are looking for. Nations Photo Lab, Mpix and Printique are generally considered really good. I've had a few large prints made at Costco which I thought were good quality and priced...