Now I know this sounds crazy, and believe me it's not ideal - but while on my conference trip in Seattle I want to get to Vancouver and back in one day.
Reason - very good aussie friend who lives in Vancouver and due to complicated visa applications etc isn't able to enter the US - so if I want to see her (keeping in mind I'm coming from Aus) then I must go to her. Due to time constraints I can only take a day.

So it seems like either a shuttle bus or Amtrak will get me there at about 10.30/11.30am and take around 4 hours. Return trips leave around 6/6.30pm. Price is similar, approx $60 return.

Given the choice, would you take the bus or the train? I am leaning towards the bus as it gets in a little earlier. Of course flying would be great but is about $250 so out of the question!!

Would you consider renting a car for the day and driving up and back? It's less than 4 hours and that would give you more freedom. If I remember correctly from your other posts you are staying at the Westin, right? The hotel could probably easily arrange a car rental.

I want to say it is about 3 hours to Vancouver from Seattle but it has been a long time since I have done the drive.

It is less than 2.5 hours from Seattle to Vancouver. It can be done in a day by car. My husband and I did it about 2 years ago; it is a lot of driving but well worth it!

I think a non-US resident renting a car and driving (assuming this is in the near future) is an invitation for significant delays at the border, making the train or bus competitive in terms of schedule. The border delays at the highway crossings can be unpredictable but seldom less than 30 min, and often an hour or more, negating the time advantage over the train or bus.

The train is much more scenic and comfortable than the bus, so I would go with it, on the assumption that flying is too expensive.

Thanks for replies.

I did initially consider the rental car option - however we are non-US (we being myself and Mum!) citizens and I was concerned at possible border delays.

If the train is more comfortable then we might take that option. I think the earliest Amtrak will get there by train is 11.30am though, but perhaps the comfort outweighs the time (bus would be 10.30am)? I think the reason the bus takes 4 hours is all the pick-ups it does.

If the train schedule works, I'd go for Amtrak. It is always more comfortable and more fun than a bus.

Here's the other option I just thought of - catch the bus the night before (there's no train) and arrive in Vancouver at 12.35am - hopefully be able to stay at friend's house - and leave at 6pm on train.

What would be worse? A late arrival allowing 17.5 hrs (inc sleep!) or an early start and only having 6.5 hrs there?

I think that depends a lot on your friend. What sort of transport would you have upon arrival? Would your friend be able to pick you up or would you need to take a cab or public transit? Is your friend okay with your spending the night? Also, would you be missing anything you might rather do in Seattle the night before? It would give you more time to spend with your friend, though you might get less sleep. I'd choose that option if the logistics worked.

How will you get to your friend's house once you arrive? Vancouver is a huge city.

I think the train would make this idea the most fun trip. I think renting a car would be the quickest.