[sonick]

There's always pockets and areas of each city that are less touristy. Trastevere in Rome comes to mind, as well as the alleyways off Las Ramblas and Gothic Quarter in Barcelona.

Of course all the major sights and attractions will be touristy. Be sure to research online for ticket policies and such for monuments and attractions; the tour guides outside the Vatican, Colosseum, etc. are very hit or miss and pretty shady. Many of the admission-only attractions in Rome you can pre-buy tickets online which also gets you priority, front-of-line access.