When visitors ask me where they should go to eat when visiting Banff, I usually direct them instead to nearby Canmore. Albertans often take the approach of "leave Banff for the tourists" and we look to nearby places that aren't quite so crowded, over-priced and often mediocre. If you have to eat in Banff, I'd recommend the excellent Sunday brunch at the Banff Springs Hotel.
There are a number of reasonably-priced quality places to eat in Canmore. I've previously shared the Grizzly Paw Pub. An equally good or even better option is the Rocky Mountain Flatbread Company,
As the name implies, it specializes in pizza and they make it fresh and tasty, often with locally sourced and organic ingredients. Soups and salads are excellent and options change somewhat with the season. Pastas and deserts are also available, though usually I stick with pizza and a salad when I visit. You can watch your pizza being cooked, but on a nice summer day with the patio windows rolled open, it's hard to compete with views of the lovely Rockies so near by.
The restaurant gets very busy so try to arrive early to avoid waiting. There's an annex open in a small mall in downtown Banff which is also good, and two new outlets in Vancouver B.C. which I've never visited. But Canmore is the mothership, so give it a visit if possible.
A sample of some of the food we've enjoyed at the Rocky Mountain Flatbread Company:
For kids, Grizzly Paw Cream Soda or Root Beer are terrific.