Well I Drive Edmonton to Penticton all the time for family vacation so can give a few recommendations of nice stops and things to do.
-Calgary - Heritage Park (open air museum), Calgary Zoo
-Drumheller - Tyrell museum, Badlands, Hoodoos, Atlas Coal Mine
-Banff - gondola, Johnson Canyon (if your little one is in a sling or backpack), Cave and Basin, Banff Falls and historic Fairmont Hotel - hiking galore of course as it suits your fancy.
-do check out the excellent Takakkaw waterfall by little Fields on the BC side - there's a cute cafe in Fields too
-Revelstoke - your little one might be too young to enjoy, but the Enchanted Forest is fun stop for kids and it's big forest cool and relaxing for adults.
-Vernon - Davidson Orchard is nice, there is a historical site called the O'keefe Ranch too which has an old house/mansion you can tour
-There is a kangaroo farm in Lakeland county which is fun
-Kelowna has a nice downtown for lunch/shopping
-Okanagan - Summerland/Peachland/Naramata wine route/Penticton waterfront - lovely area. Kettle Valley Steam Train, Ornamental Gardens...pretty. The lakes will still be bit cold for swimming
-Vancouver there's of course lots to do and it's a beautiful city. Don't miss the Aquarium, Granville Island, Capilano Suspension Bridge, Grouse Mountain - maybe little trip to Whistler.
Have fun!