Byron,
If flying into Vancouver, be aware that the Rocky mountains are a gentle 2 day drive east, it is worth doing this at least one way as the scenery is so spectacular (Cam loops, Glacier NP, humming birds on the bird feeders, Revelstone dam). We based ourselves intially near Banff, took a few days to visit Lake Louise (still ice covered) and do some shorter walks (still thigh deep in snow in May). Saw lots of black bears.
After leaving Banff we drove north on the Icefields Parkway, worth spending at least a couple of days over this, visit the columbia icefield, waterfalls etc then onto Jasper, we went walking and whitewater rafting in Jasper before driving back to Vancouver.
We visited mid-end May and this was really shoulder season, no good for skiing but too much snow for the walking trails to be fully open. The big advantage of this was that accomodation was very easy to find, we booked a fly-drive package with no accomodation and simply used guide books to locate a likely place and turned up and asked if they had spare rooms/log cabins etc.
hth
StarGazer
ps if you like trains, at Cam loops you can see the mile long trains (we lost count at over 100 wagons) with 6 engines (2 front, 2 middle, 2 end) exiting the big spiral tunnel before the tail of the train has even entered.