Cool!
Cavalieri Rome - Cat 6
Airport Hilton Rome - Cat 5
Airport HGI - Cat 4
One thing I noticed at the airport Hilton, their shuttle bus to downtown runs quite late, I think about 11:00 PM - at any rate, much later than the little bus from the Cav. Also, the airport is about 5 minutes from the sea and the little picturesque-but-seldom-visited town there (can't recall the name).
Why they put another Hilton at the same airport I don't know, but it sure is nice to have other choices in Rome. Especially if you're not a Diamond and can't get into/get the perks at the Cav.