I've stayed once at a standard room at the FCO Hilton (with the compliments of Alitalia, of course!) , and I found it rather appalling for a supposedly high-end property.
Wallpaper peeling off, welcome screen on the TV displaying wrong names, a couple of empty shampoo bottles left in bathroom, a rather worn out mattress and so on. Nothing really major, but things that are out of place in anything pricier than a Formule1.
There are a few hotels in the nearby town of Ostia (there is a local bus going there and it takes about 12-15 mins).
For example, a double at the Ostia Antica Park Hotel costs 77 Euros (it has a shuttle but it charges €10 each way), or you can try the less impressive La Scaletta which is in the town centre and on the bus route to FCO.
IMHO any hotel or B&B in Ostia has the €120 Garden Inn beat hands down.
The Hilton Garden Inn at DFW (random USA place I checked) costs $79 per night. It's essentially the same product as the FCO one, which is squarely aimed at people from a certain foreign market.