The area around the train station is improving greatly, but I think you would be best to get on Sky train right away and head into downtown. Lots and lots of nice places to eat. After a trip like that, I'd go for a corner bakery cafe.

Grandville Island is most interesting during the day when the Market is open. It goes very quiet there after 5 pm, although there are a couple of theatres and some very nice restaurants.

If you are in Stanley Park, perhaps stay around the Beach Avenue, Denman Street neighbourhood. Lots of life and action around there on a sunny summer evening.

I hope you realize you are taking the amtrak BUS not the train! There is one train daily which leaves Seattle at 7:40 am arriving in vancouver at 11:30 am. if you can possibly change to the train I would for two reasons.. one is the scenery.. the train travels along the coast with beautiful scenery. The bus travels the I5 highway corridor.. ok but not much to write home about...second is you would arrive in Vancouver earlier which would give you more time to see things. Granville Island is much better in the day time. All the artists shops and the market will close by 6 pm. There are some restaurants there but the majority of what you want to see will be closed. If you don't come earlier I would still visit Granville Island first and then make your way by Aquabus ( watertaxi) across False Creek to downtown (English Bay side of False Creek 5 minute ride) and then walk along the seawall into Stanley park.

I understand what others are saying about Granville Island being more active during the day - it is. But I still love it at night after the crowds leave - and I find window shopping much cheaper than the other kind. There are lots of good places to eat there (and if you're interested there is the Arts Club Theatre which presents plays and improv comedy). From previous posts on this forum I learned about the restaurant website for Vancouver:

http://www.dinehere.ca/results.asp?l=24

and from that picked where I am going for my next special dinner - the Afghan Horsemen on Granville Island (can't comment yet - still in my future). Admittedly, this would not serve very west coast fare, so if you are inclined towards that, there is Sandbar and Bridges. Both those restaurants are on Granville Island and both offer good food in great locations (I think the patio at Sandbar may be one of the best patios in the city and you can sit there rain or shine and enjoy it). Both do lunch and brunch so if you decide to spend the daytime part of your day there they are alos good options.

If you do decide to reverse your day, there is also the fish house restaurant in Staley Park for a very nice dinner: http://www.fishhousestanleypark.com/

To throw another idea in, Queen Elizabeth Park (and nearby Van Dusen Gardens) is also beautiful (although not downtown) and has Seasons restaurant with great food and a panoramic view over Vancouver and the mountains. www.vancouverdine.com/seasons/home.html

I agree with traveller47, that time schedule is strictly by bus, not train. If you can take that morning train I would strongly recommend it. A much better view into Vancouver. If the weather is great, it should still be warm enough to enjoy a meal on Granville Island on a patio. Check out Bridges restaurant, or if time is not permitted, there are some nice places in the food market, inside the Public Market.