Spent 2 nights in Vancouver last summer and we're leaving from there mid June on H/A. I exchanged dollars while there at a bank, also saw exchange places downtown, tried to use credit card when possible. Message boards say US Dollars can be used, expect the exchange rate will vary.
Stanley Park was good, went to the aquarium. Walked around downtown(robson st) one night. Highly recommend Granville Island Public Market. Taking the Water Taxi from south downtown is half the fun, there was a nice hole n the wall fish n chips place round the small bay in back of the market that had some great halibut.