Consider bamboo flooring, as well. It's ~25% harder than oak, and is considered a "green" (Earth-friendly) wood because of how fast it grows. We were planning on bamboo flooring from Teragren
, but ended up buying a bunch of used oak flooring (pulled from an American Eagle store) from a guy here on greatlakes4x4.com. I'll be installing & refinishing that myself.
We want a "lifetime" floor, so laminates were quickly dropped from the running for us.