I like careerboard.us, U have to market it well tho as .us sales are not that frequent.
I'd drop The other two names(Most of the registrars offer a refund within 5 days of the name registration if you don't like the name. You have to call them tho). You can look at the .com,.net versions of the two names, all are parked. If you are starting new, Start with .com and read more in the forums.Good Luck.
Thx.