What you didn't state is what country you are in, however, I would guess, most likely in the USA.
What I would also look into is to try and research where wedding and portrait studios in your area get their prints made. Some professional labs do deal with the general public as well. If your standards are exacting, that may be a good bet.
At least from my experience here in Melbourne (Australia) is that labs like The Edge offer the widest range of print sizes (almost anything you can imagine) and they only use archival paper. What has also been an eye opener for me is that some pro labs are cheaper for larger prints (e.g. 11x14 and larger) and will also have access to some more interesting print finishes the Kodak Endura Metallic (that is just a personal like for some prints).
If you are using a lab that also services studios, you know their quality will be spot on, as they have a lot of very demanding customers.