[pwarshaw]

Would bamboo floors be okay to put on pier and beam floors and would bamboo floors be a good choice for the bathroom?

 

[Millertyme]

bamboo is a terrible choice for a bathroom especially engineered. If it water gets between the flooring it will stain it and make it swell up. I have seen this twice in as many bathrooms

 

[SuperFloor]

Any bamboo or hardwood flooring (solid or engineered) would be a terrible idea for a bathroom. If you get any water between those planks it will ruin the floor.
You may get away with a laminate, but that's still not such a great idea. You would be much safer thinking about ceramic tile (or the like).