I think we have thermafoil in our powder room as well. You're right: it can't be painted.
You're right about espresso not being "in" right now. Bathroom trends echo kitchen ones so it's all about white, painted or natural wood vanities now. That said, trends schmends is my motto when it comes to deals. :P Practically anything can be made to work, if you've got a vision. Besides, espresso is "off black". Pretty neutral and classic, all things considered. I like the lines of the free standing Lowes one you linked. Versatile. Not overly modern or traditional. Will you be able to see it in person to check the quality of the finish?
The hickory floor you've chosen looks neutral enough to not limit your palette choices. Will this be the floor in the hallway next to the PR as well?
With an espresso vanity, I'd be tempted to go with a very light floor for contrast. This type of idea (which can be achieved with affordable vinyl):
Hey, didn't you do your kitchen recently? Perhaps that could inspire the PR choices?
Q