All depends on your age and much you want to spend.
If you have a bit of cash to burn and are in your early 20s or older, this will work.
Bring your Gf up to Whistler.
Then bring her to here:
Scandinave Spa Whistler. Your Day & Resort Spa
Very relaxing and intimate.
Then go for dinner and walk around in the village. Not much to do, but allows you to "walk freely and romantically"
Stay overnight in a hotel, and see where the night takes you.