I would ask what the OP means by a "good travel credit card".
First to the question of Canadians getting a US CC, it is possible, and it is not so much about having a US Social Security as it is about having a US Credit Bureau. Now generally if you have a credit file in the US you have either a Social Security number and/or a bank account, but the point is no lender will extend credit if they come up blank when you they go to TU or Experian to check your credit history. You can have a social down there, but no credit bureau and you most likely still will not get a card.
Now to the question of travel credit card.
If you mean a
travel rewards credit card, starvenger's URL will take you through many options. Things to look for are how rapidly you will rack up reward points, and how difficult it will be to use them. As a long time ex-banking exec (credit card), I avoid these cards, as they are generally not worth it FOR ME. I don't rack up points quickly enough, and I hate having to go through hoops to use them. However, the best of the lot are probably the ones that allow you to book your own travel, anywhere, any time, and then claim back the money spent as a credit through a simple process. IMHO, Hotel and Airline cards? Ugh!
If you mean a
travel card that provides good coverage for insurance or travel, most of the high end bank cards will do this for you. I use a Gold Elite visa for travel booking and rental cars. It provides all of the trip cancellation, insurance, and medical I need when I book with the card. It also provides cash back as a percentage of my spend, and I have a no-fee deal with my banking institution, so it is easier TO ME to get the benefit back (I like cash better than trinkets or free nights). However, if I am paying in US dollars I generally flip the final payment to the next option below.
If you mean the best
card to use for purchases while travelling, follow Blackadder's advice. The Amazon.ca card does not charge the 2.5% exchange transaction fee that all the other cards (except Sears MC and Marriott Visa) do, PLUS gives you another 1% cash back. And that is money in your pocket. However, the card has no protections for travel arrangements (cancellation, health, or auto), so don't use
Amazon when booking these items, even in US dollars (the insurance is worth the 2.5%). However, if the payment is tail-end, and you have had no claimable issues, don't be afraid to put the final payment on the Amazon card. So book your US hotel or car rental on your travel insured card, and then when they ask for final payment, use your Amazon card to reap the savings.
As an "insider" I have no problem maximizing my advantages with my CCs. Believe me, the credit card issuing companies invest heavily in understanding how to maximum their return on their relationship with you. Nothing wrong with doing the same thing back to them...