The Rossio area is my favorite place to stay. Yes, it can be touristy but you can avoid doing the touristy things. It's convenient for walking around Lisbon, going to Sintra, and lots of great restaurants/pastry shops within walking distance. The streets above Rossio are quiet because they're one-way tor cars and very narrow, and tend to be more residential, unlike in Chiado or Barrio Alto. I stayed once in Chiado over a weekend and did not appreciate the sheer amount of noise after 1 a.m., or how many people I had to pass trying to sell me drugs. I'll be returning in April for the third year in a row because I love Lisbon so much.