I am not aware of much in the way of scuba shops outside of Denver area, FT. Collins, CO Springs, Telluride and maybe Pueblo. CO is a great place to ski......diving not so much.
Certification is a two step process, pool/ classroom, and checkout. Checkout is a two day process as new divers are limited to three dives a day, and four dives are required.
You could travel to Denver for one or both sections of the process, but each section really requires two days for a total of four days. This dos not include Book study, and I would recommend at least one week to cover that on your own prior to classes. A1 does a good job and you may want to call and discuss things with them or some other shop.
Costs in Denver are maybe $500 and that does not include coming away with much in the way of gear. They will make it seem cheaper, but by the time you add up the materials, dive gear rental costs, gas, certification costs etc, its about $500 in CO.
You can also do the checkout while on vacation. There are many options, so call and discuss with the LDS of your choice....