Q: by the time we get through customs it may be about 11.30 pm or more and i dont have any canadian cash only travelers cheques so will there be any travelex open in vancouver international airport

A: There might be a money exchange open, but I don't think they cash travellers cheques Just bring US cash or a credit card like Visa or Master Charge. Travellers cheques can be cashed at banks the next day or possibly your hotel when you get there US currency is widely accepted.