If it makes any difference to you, find out what species of wood you'd be
getting from China. That country has a reputation for putting environmental
concerns about 50 years behind business development. In other words, they
don't give a damn.

As far as hardwood in general, be prepared for squeaks which are louder than
normal conversational speech, chilliness, and quite possibly very sore feet.
On the plus side, the squeaks make an excellent security system. If you're
100% sure that everyone's in bed and the downstairs floor is squeaking, it's
time to load the shotgun.