From a business aspect point of view, the only thing I could see this domain being used for is for a domain registration service for the .us. However, it is way to ealy to determine the .us value today. However, I'm a strong believer of the .us, and I think it could be one of the best TLDs in the future. Of course the .com will alway be no.1
My advice to you would be to use it yourself and see if you can find an affiliate for the .us. The domain together with a site will be worth a lot more then. I also think a lot of potential buyer will fail to realize what it could be used for if you don't develop a site first for the domain.