Seattle to Victoria ferries it depends whether you're traveling with vehicle or not...the Swartz Bay-Tsawwassen ferry takes only 2 hours, while the ferry from Sidney (north of Victoria) to Anacortes takes around 3 hours. However, the most direct way to get from Seattle to Victoria is by Victoria Clipper ($97), which is a passenger-only ferry. All Seattle Tours also has a direct ferry to Victoria which costs $84.
That's not too bad for a ferry ride... it actually costs less than I expected for the trip. Victoria and Seattle both have a ton of great things to do, so it will be worth it to make the trip. I bet Victoria is just beautiful now that it's spring.
You also have to factor in driving distance to get to the respective ferries. The first ferry mentioned in Sourlko's post is a ferry from the Vancouver, B.C. area to the Swartz Bay terminal on Vancouver Island - about a 20 mile drive from Victoria. However, you would first have to get from Seattle to Vancouver which is a long drive in itself - more than 2 hours. To take the Anacortes ferry you would have to drive about 80 miles from Seattle. Be careful what you ask for!
Downtown Seattle to Downtown Victoria on the Clipper...takes about 2.5 hours and is a fun trip and about $100. Victoria is well worth the trip! As is Seattle the other way.
I was thinking that $100 sounded like a lot, but not really, if you consider how long and comfortable the ride is. Thanks for the advice everyone!