May I also recommend Elk Island Park just east of Edmonton. Some lovely hikes and you will see Buffalo. Near the same area is the Ukarainian cultural village. It's pretty neat and the kids might like the hayrides. Both of these things could easily be done in a single day.

If you're flying out of Edmonton, you can do a loop of Edmonton-Jasper-Lake Louise-Banff-Drumheller and back via highway 2. I live in Edmonton and we go camping in Jasper several times per summer it is my happy place and if you want more ideas specific to that area, I can give you a ton.