We hired a car from New York and drove to Canada which they were fine with but we returned the car to the same place in New York as that is where the return flight was.
It was through Dollar rent a car (or something like that), we've always found them to be the cheapest on longer holidays, but that is with the bigger sized cars... not sure how their prices compete with the other ranges. Actually come to think of it, we hire with Dollar whenever we go to San Fran or to Florida as well and have never had any hassle.