Castel Sant'Angelo has a rich history. Just because it's not well marked, with signs in English for tourists, doesn't mean it isn't worth a visit. It's easy to research it yourself before you go so you'll know what you're looking at.

What budget hotel?

Cat:
Ordinarily, that's exactly the kind of experience I would relish. But we have such a short time in Rome (first timers, too) that I think I'll have to let that one go this time.

JeanneB,
I know you're not going to Castel Sant'Angelo, and I didn't make it there until my most recent trip to Rome, but I had to chime in for the record: there are audioguides to rent (in several languages) from the bookstore. They're not the most comprehensive, but they do exist.

And to 1323: I do a fair amount of walking in my day-to-day life and have never had any problems getting around Rome (to the Borghese, to the Vatican) on foot. So if you're used to a little walking, you can get to most places without bus or taxi, except perhaps the two I mentioned above in parentheses.