For sure, if you can come in off-season (which is basically late-April through May 24 weekend, or Canadian Thanksgiving through November), it will be much quieter and cheaper. But, it also depends on your planned activities. If you're coming for general sightseeing and driving around, then you have a lot of flexibility on when to visit. If you're coming for the great hiking, then spring just will not work, as the alpine hiking season only really starts in July (or sometimes mid-June on a year with a hot/early spring) and is done by end of September. The good hiking trails are still full of snow well into June.