Well, first off, do you have a passport or a birth certificate? If you don’t, then you can’t visit Canada. There should be pages here that answer those questions.

The train from Seattle to Vancouver costs a little more than it used to, but it’s worth it if you’ve never taken it before. I think it’s between $35-$43US, depending on which train you take. The morning train from Seattle to Vancouver is a little cheaper. There are many more Amtrak shuttle buses that go up several times a day that are cheaper. http://www.amtrak.com has all the info.

You can get a deal if you take somebody with you, if you get one of those Chinook Books ($20) at any Seattle co-op market. I think there’s a deal where you get a heavy discount on one Amtrak Cascades ticket if you buy another first. That alone will pay for most of the book itself, and you get a lot of other coupons to go with.

What to do in Vancouver? Heh, you should ask that as a separate question under the Vancouver listing. Trust me. Best place to stay? Yup, ask that question under Vancouver, too. :)