There are lots of good boats for big guys these days. It's always good to shop local, but good info can be found on www.coloradokayak.com
. Both are long-standing, well-stocked outfitters.
They can help you decide on types and sizes. If you've never boated, I highly recommend a clinic from a good school - which both CKS and NOC have. Confluence Kayaks in Denver also has a rep for being great at teaching/introducing people to the sport.
Welcome, it's a great pastime.