Mario and Valeria's apartment is the perfect place to stay if you want to walk around and get your shopping done. There are great restaurants in the vicinity and it's shopping central. It's literally less than a minute away from the Spanish Steps and taxis are immediately to your right as soon as you walk out of the building, if you want to go somewhere else.
Valeria was a fantastic host. She was very helpful. All you need to do is ask for something and she will get it done for you. I definitely recommend this apartment for the next time you're in Rome.