Hmm..
let me see, from what i have experiance and read about other
peoples experiances:
1) Detroit/Windsor: lot of people complain about initial landing
, sometimes getting denied.
2) Buffalo and Niagara: I have crossed in each place in both
direction once, never got checked, even did not have to show
my landing papers ( using early morning greyhound at the border,
having started from NYC the prev night I was at the peace bridge
at 5: am , all the passengers were just waved thru ). Later
at niagara I walked across to the canadian side, I was carrying nothing just car keys...so looked like a tourist, again let in
with just ..do you have your papers..yes ).
3) Aldergove is a straight north from belligham ( search in
www.vancovuer.hm for border corssings for a detailed list
of border crossings ) . Very quiet small town place, no traffic
ever. we crossed over by car , just a few questions at the toll
booth kind of customs office and were let in. Other place I crossed
was at the truck crossing at Pacific highway ..here is where I
crossed over while landing, again just the usual qs and we were
done with the landing in 10-15 minutes.
All of these are 5+ month old experiances. My gut feel is to use
greyhound or quickcoach out of seattle airport to vancouver, I think
that should be the easiest. since driving a US plated car is not
allowed for Can residents.