I researched this a couple of years ago and found US operators a lot more picky about PPL rental (a 172 to go to Nevada) than Canadian ones, and more expensive. More than one Seattle FBO expressed a reluctance to rent for flights in mountainous terrain! I settled on Canada instead.
The downside was needing to obtain a Canadian licence, as there is no reciprocal that will allow you to fly PIC internationally to the US. However, the club (PFC at Boundary Bay) was excellent and aircraft more available than on the US side of the border.
The checkout involved 3Hrs mountain training which was worth the trip in it's own right.
Just don't forget that there is no visa waiver system for private flights - nobody at PFC (all Canadians) knew that and I didn't find out until US customs told me on the morning of departure, which then required a frantic drive to the nearest border post!
However, if you do decide to fly on the US side Olympia is a lovely field with several FBOs and well away from the busy SeaTac area.