Anywhere on Vancouver Island. Just pick a spot, and it's nice. One time we took the ferry to Gibson's Landing from Horseshoe Bay, then crossed over to Nanaimo on the Island, then down to Victoria and back by ferry to Tswassen. It was a beautiful trip. In the summer at night Victoria is really gorgeous down by the harbour. Everything's lit up, boats included, there are flowers everywhere, and buskers for entertainment. It's never hot, and never cold. Quite an amazing place.
Other favourite places in B.C. are the drive up the TransCanada through the Fraser River Canyon, going through Hope and past Hell's Gate. Also the Okanagan in July for cherries, and August for peaches. Yum!!!

I second the Barkerville suggestion. Old gold mining town, sort of like Deadwood used to be before the casinos moved in.
In Alberta, the Tyrell Museum at Drumheller is world class, and worth the trip all by itself.