the PanAm Hwy sucks
While I didn't ride a whole lot of the PanAm, the stretch through Costa Rica was the worst of the lot. No potholes, but very rough from patching former holes.
And if you're going to follow the Pan American, then you'll go out of your way, like into Managua instead of cutting that section out on your way through Nicaragua.
Stay flexible - the PanAm Hwy is for trucks - and its for people want to get through CA as fast as possible. Its like taking the freeway in the US, you don't see much.
Chiang Mai, Thailand