In a parking lot. Sorry Les, I could not resist. I can't say that I have had to drive to Vancouver, so I can't offer any real advice. Maybe someone else can.
If no one offers up suggestions, I would say to start a Google search and find out what you options are before going. There are ports that have not cruise line or port affiliated parking companies that offer parking at a reduced. Maybe they offer that in Vancouver.
Are you staying overnight in Vancouver? Many of the motel/hotel offer cruise and park packages. My wife arranged our room, but she said it was less than paying for parking at the cruise terminal. Traffic around the terminal can be very busy, the hotel will shuttle you over and back, depending on your package.
Also be aware if you are crossing the border it might take awhile. It would be ashame to miss your cruise because you were tied up at the border.
I have not chose a cruiseline yet, any suggestions on an Alaskan cruise? My plan would be to go in July or October. I wish to leave from Vancouver because I live in Calgary Alberta Canada. There is no border crossing this time.
Are you wanting a round trip, one way, or a cruise tour? We have done the HAL 7 day round trip out of Vancouver twice, will do it again. It hits the 3 big ports, plus it does Tracy's Arm and Glacier Bay. It packs a lot of bang for the buck.
(edit to add) BTW you will not be taking a cruise to Alaska in October. The end around mid September.
You will find many cruises leaving from Vancouver. The Alaska season will end mid/late September. June/July/August are prime time. All the major cruise lines sail Alaska. Princess and Holland America have been up there the longest. Other cruise lines such as Carnival, Royal Caribbean, Norwegian, and Celebrity may be better suited to you. They also have luxury cruise lines sailing Alaska. I would recommend you find a cruise specialist in your area to talk to, that can help you decide which cruise line meets your expectations and life style.