I was very pleased with the service I received at Ann's Hallmark. They helped me order the invitations that I wanted (they have a TON to choose from), and kept me updated on the progress of the printing, shipping, etc.
It was easy and simple to look through all of their album of invites. You do need to order about 4 months in advance to make sure you have everything correct on the invites and that they are there on time in case something goes wrong. I like Hallmark because they are priced pretty low.