This is such a great idea! I wish we would have done this last year when we were in the same situation. We did it all wrong! We took a suggestion to use a company that advertised locations to drop off bags at various retail spots in the city, then took buses to various places we thought we wanted to visit. Big waste of time and effort!
With a car and google maps, we would have done much better!
Have done the HOHO bus in Vancouver on a previous trip. We did get a thorough look at the city with it, but remember with the HOHO you are at the mercy of the timing of the bus schedule at each stop. A car is the way to go!