Lake Louise area : Lake Louise is 45 minutes' drive from Banff townsite.  The lake of Lake Louise is 5 km (3 miles) from the village of Lake Louise.  Although Lake Louise is an icon that certainly is worth visiting, smaller and lesser known Moraine Lake is — if anything — even more beautiful than Lake Louise.  Moraine Lake is 14 km (9 miles) from Lake Louise.  If you do one of the lovely half-day hikes in the area, that's about all you'll be able to fit into a day.  If you do not go for a hike, you should be able to add the Spiral Tunnels, Takakkaw Falls, the natural bridge over the Kicking Horse River, and Emerald Lake — all of which are in Yoho National Park, to the west of Lake Louise.

Columbia Icefields : The Columbia Icefields are located half way along the Icefields Parkway (Hwy #93), the scenic route that connects Lake Louise and Jasper.  They are about 1½ hours from Lake Louise, so about 2¼ hours from Banff townsite.  A popular activity at the Columbia Icefields is a Snocoach ride onto the Athabasca Glacier.  Rides on the Snocoach are sold on a first-come, first-served basis.  How fast you get onto a Snocoach depends to some extent on whether or not you happen to arrive behind a couple of big tour buses.  The worst case scenario is that the entire exercise — waiting for the Snocoach and the ride itself — will take 1½ hours.  While you're waiting you can view the Visitors' Centre's interesting display and explanation of glaciers.  If you are a very active person, you may prefer to do a guided walk onto the Athabasca Glacier (reservations essential).  A scenic landmark that is worth seeing on the way to the Columbia Icefields or on the way back is Peyto Lake.  It's just off the Icefields Parkway, about ½ hour out of Lake Louise.  Its colour is very special.  It would be good to drive just as far as you feel comfortable before turning around and heading back to your base in Banff townsite.  You may be able to get as far as Sunwapta Falls, about 50 minutes beyond the Columbia Icefields.  If you visit Peyto Lake, ride the Snocoach at the Athabasca Glacier, take an hour for lunch, and visit Sunwapta Falls, you might be looking at a 10-hour day.   

If you are driving yourself around the Rockies, you should consider renting a GyPSy Guide or Sawka Tour Guide.  These are GPS devices that automatically play audio tour commentary when you arrive at particular points in your drive.  Everything from geography and history to stories about where to watch out for wildlife and quirky Canadian tales. Great if you want to still learn about the area and what you are seeing, but don't like the idea of a guided tour bus or dealing with printed information instead of looking out the window.