Cody,
Welcome to CCR!
I think your plan to get comfortable on local lakes is a great idea.
You should purchase Mark Lund's book, Mark's Guide for Alberta Paddlers. (Available at a number of outdoor stores and MEC -
http://www.mec.ca/shop/?q=Mark's%20Guide It is an excellent resource and will give you a good idea of many runs that would be suitable for beginners including flow levels that would be appropriate for you.
I imagine there are a number of paddlers in the Sundre area. When you see a boat on a vehicle, stop and talk. Although many of them might be whitewater paddlers, they will have knowledge of local streams where you can have an enjoyable and safe paddle. I imagine there are some small creeks with stretches of very easy water that would be good places. I've found that many people enjoy "muskeg" creeks and they are a good place to learn how to maneuver.
From experience, it is especially important for your "nervous" wife to have good experiences, especially early on. If you push her envelope too much, too soon and she has a bad experience, the end result might not be what you are hoping for.
Have fun,
Ralph