OK, first thing to know is the real mountains, not the foothills, are an hour's drive away.
As for info - try looking through this site from Parks Canada about Banff and area.
http://www.pc.gc.ca/eng/progs/np-pn/sp-ps/sec6.aspx
There are all kinds of things to do. Try this link for the Banff/Lake Louise Area: http://www.banfflakelouise.com/things-to-do/summer-adventures
If you want a little bit of a refresher after walking/hiking, the Hot Springs are great - you will come out smelling of sulfur, but that's the price of being able to relax in a really big hot tub ;-)
I've climbed up through Johnson Canyon which is west of Banff.
http://www.banff.com/hiking/johnston_canyon.shtml
If you've got time, you should travel north to Jasper, on the Icefields Parkway (aka Banff-Jasper Parkway). About halfway between Banff and Jasper is the Columbia Icefields. Water from the melting ice eventually end up in three different oceans: Arctic, Atlantic, and the Pacific. There is a company which will take you out on the glacier itself; the downside is that the trip is rather expensive at $50 per adult.
Parker Ridge is approximately 2 1/2 hours north of Banff http://peakery.com/Parker-Ridge-Alberta/. There you can hike without needing hiking gear - depending upon the snow pack, you might be able to throw snowballs (I did with my family, on July 1st one year). You'll also find interesting fossils of plants and animals that now inhabit the oceans, demonstrating that part of North America you walk on today was originally under thousands of feet of water. The Rocky Mountains were formed when there was a ginormous earthquake which thrust the land up thousands of feet like you see today (BTW it's illegal to take any of the fossils with you.
As you go further north, take time to see the Athabasca Falls - they are truly beautiful and awe-inspiring. Note, the water going through these falls will eventually go through Fort MacMurry, Alberta, and the tar sands.
Finally, Jasper is a great little place, and IMO much less touristy than Banff. Worth the trip to see and to compare with Banff.
Wow, this is sort of a trip along memory lane because I've been to all of these places on numerous occasions. When you're in Banff, you should meander down Banff Avenue - there's a great place which makes the best fudge while you watch through the windows.
Hope you really enjoy your time...