Trying to see if there's a car ferry from Seattle to Victoria. I've found a passenger-only ferry, and a car ferry from other points in Washington, but nothing from Seattle. Looking to do this in June.
Advice??

I don't think there has been a car ferry from Seattle to Vancouver Island for a long time (not sure if Princess Marguerite was passenger-only or car). Basically the journey would take too long and cost too much. I think Port Angeles-Schwartz Bay(?) run is your only option for Washington state-Vancouver Island.

Port Angeles-Schwartz Bay is not a good option, rather take Annacortes-Sydeny which will save lots of time. Annacortes is around one and half hour drive from Seattle.

http://www.wsdot.wa.gov/ferries/schedules/current/index.cfm?route=ana-sid

Here is another ferry:
http://www.cohoferry.com/
from Victoria-Port Angeles car ferry.

Though they only take cash and do not take advance reservations. Though I don't know how much of a drawback this is

Here is another ferry:
http://www.cohoferry.com/
from Victoria-Port Angeles car ferry.
we took this ferry and it was great as they had a late evening (7:30pm ish) departure. crossing was 80 minutes if IRRC.

If you are traveling during peak times a reservation might be peace of mind, so perhaps the Washington State ferry route that hka_mm mentions above would be a good choice.

There's also a ferry from Anacortes to Sidney on Vancouver Island which takes around 3 hours and runs once in each direction a day at the moment. It'll take you slightly less time to get to Anacortes than it would take to get to Port Angeles, but the ferry time is less form PA. I'd go for the Anacortes route personally as I find Port Angeles a little sinister after dark ;)

-- edited to say I didn't see the post about the Anacortes - Sidney ferry until I posted but deleting is always a little rude.