I think the LLL.info market has been a bit up and down recently in reseller terms, but your two here are really good. I especially like aux.info, which has a lot of uses, and would make a great domain for a tech-related site. Iuu isn't devloped in as many extensions as far as I can see and has fewer commercial applications as an acronym, but it is still a good combination. Rails has less of a reseller market available, so does is not as liquid as an asset as the other two, however has some end-user potential. In summary, this is how I would value them if they were mine:-
Aux.info - Absolute minimum reseller value $500 (would probably not ever sell at this though), would be looking for $xxxx
IUU.info - $200 reseller.
Rails.info - low $xxx reseller, many rail manufacterers/distributers though, would be chasing these for $xxxx
As mentioned though, I think the reseller market for .info will be stronger soon.