We recently returned from a week long stay at the Hotel Giada, a simple, smaller hotel with a nice small-ish but adequate size room, newer or remodeled clean bathroom, a big operable window overlooking a typical Roman street, marble floors, quiet, and great staff service; all for about $190/night. It's not the Ritz, but much nicer, quieter, and classier than a Holiday Inn or Motel 6.
Of course the hotel is older (it's downtown Rome, remember?) but it seemed very well kept up. I can't comment on the heat or A/C; the temps were just right when we were there, so we didn't have anything turned on.
This place is really centrally located, close to the train station but in walking distance of the coliseum, forum, trevi fountain, and a host of other places. Of course restaurants are everywhere close by, and all the other 'corner stores.' The public transportation in Rome is great, and you can get to anywhere from just down the street.
We tipped the house keeper 5 Euro's a day and she did a really nice job.
The front desk guy spoke pretty good english, and was quite informative about which bus or train for us to take. He called the American Catholic church for us and arranged tickets to see the Pope at his Wednesday audience; and, got them delivered too! It's amazing what just a simple pack of American Marlboro cigarettes can do for you!
We have been all over the world, and have stayed in the best and the worst; I would recommend the Hotel Giada, and we will stay there again when we are in Rome the next time.
Incidentally, on previous trips to Rome, getting out of the train station was a hassling experience - threading through rogue taxi drivers, gypsies, and what not. This time there wasn't any of that. Maybe it's all those cops with machine guns everywhere? Still, keep your guard up and valuables close to your vest.