Things To Do
The Canadian Rockies provide not only a beautiful wedding backdrop but also plenty of activities. Do note however that the average low/high temperature in late April is ~30/54°F, so pack and plan accordingly!
Historically the ski resorts close in May, so we're hoping to get in some spring skiing. Some of David's favorite hikes in the world are also here in Banff National Park. Since there will still be snow on the ground and ice on the lakes some trails & roads may be closed; make sure to add "in winter/spring" to your "things to do in Banff" search.
If it's cold you may enjoy just eating & drinking your way through The Fairmont Banff Springs hotel, which is huge and a thing to do in itself. The town of Banff is also very cute (we'll let you guess based on the map what Emily's favorite spot is).
In addition to the recommendations on this page there are probably more than a hundred other wonderful things to do and see, with or without access to a car.