Wait-a-minute... this isn't the wrong thread... someone merged these threads while I was typing, I think! This is what I was going to say before I deleted my post, thinking I had posted into the wrong thread!
<Chuckles> I was just about to link to my previous post on the topic, too... I'm glad some teams have found it helpful. The other advice here is good, too.
We drove across the border many times for Portland and Seattle FRC regionals and never had a problem. Nobody has ever asked for our lists of tools, spare parts, or paid more than a cursory glance at the permission forms... but the thing is: you want to be ready in case someone asks.
We never had to bag and tag a robot across, but on the other hand we've moved dozens of crated VEX robots to and from competitions this year without a problem... and we never had a problem with FedEx/brokerage for FRC robots either, so long as I did all the paperwork right. I can't think of any paperwork that would be required for transporting an FRC robot personally across the border... there is certainly none involved in transporting VEX robots.
Get some medical insurance, double-check passports, inventory your parts, pack up the van and go. Can't say I envy you the drive, but the Seattle people are really friendly and you'll be more than welcome once you get there.
And I'm looking forward to meeting your team there, too... I'm doing Tech Inspection on Thursday then judging later in the week.
And next week I'm going to pop out to the Olympic Oval to lend a hand there, too.
Good luck, and safe travels,
Jason