Early april is late winter/early spring in the Rockies; the ski areas will still be open, and you should still be able to go dogsledding in Lake Louise with Kingmik (http://www.kingmikdogsledtours.com/). The other dogsledders operate at much lower elevations, and may have problems with snow at that time -- it depends on the weather. The same goes for snowmobiling, which takes place outside of the park boundaries; it's not permitted within the national parks.

As for the Icefields Parkway, I wouldn't plan on making it part of my itinerary because winter (or spring) snowstorms can close that road for a day or more; this seems to happen once or twice each winter. However, *if* you get a great forecast and a good road report, you may wish to drive from Banff or Jasper partway onto the Icefields Parkway. However, the scenic pullouts will most likely all be blocked with snow, and the only services on the road will be the food & fuel at the Crossing Resort (http://www.thecrossingresort.com/contact.html) which opens in early March. If you decide to go, make sure your car has a winter emergency kit.

For info on dogsled & snowmobile tour operators, go here:

tripadvisor.com/Travel-g659487-c72294/Canadi…

Scroll down to the appropriate heading for info.