I think the real question is do you really need your car in Seattle and how much time do you have? If you don't need your car, then take the train. Its a beautiful ride with great scenery all the way.
If you do need your car, there's a few things I would suggest. If you have a lot of time, I would head east on the Sea-to-Sky Highway to Lilooet via BC-99, then head south on Trans Canada 1. When you start seeing the signs for the US, follow those which will bring you to WA-9, a beautiful scenic route that I recommend almost year round. There's a bunch of scenic side trips off of this which you can see on http://www.myscenicdrives.com/regions/washington . With this type of trip, I'd probably recommend following WA-9 all the way and meander into Seattle that way.
With less time, I'd probably head south from Vancouver to the US border, then take WA-9 or Chuckanut Drive as a side-trip. The trip is wooded with mountain views for most of it -- as the I-5 widens, the scenes become much less interesting IMHO.
Scenic
By kayak through the San Juan Islands.
The drive from Seattle to Vancouver, BC, Canada is an easy drive that takes about 3 hours on Interstate 5. The border crossing can have long waits, especially on holidays and long weekends (both U.S. and Canadian holiday weekends.) The interstate is tree lined, so it is a fairly nice stretch of driving, though I wouldn't say it is particularly scenic. However, in the fall, when the trees are turning, it is quite pretty.
The drive time from Seattle to Vancouver is approximately 2 hours and 30 minutes. The actual driving distance is 141 miles.
i live in seattle it takes about 2 hours r u going ?
i live in seattle it takes about 2 hours r u going ?
about 2 and 1/2 hours
It is 140 mi (about 2 hours 30 mins).
It takes 2 hours to 3 hours depending on traffic
how long to ferry from seattle to vancouver canada
I-5 goes from Seattle to the Border, from there take route 99 to Vancouver.
MapQuest estimates the driving time as 3 hours and 8 minutes.