If I leave you with only one piece of advice it is that: You HAVE to see a fado show. There are dozens of over priced options in the tourist areas but I found a hidden gem called Sr. Fados located in Alfama district. It only seats 25 or so people and is open Wed-Sun night. It's a price fix without any choices, but the food couldn't be more local or fresh. The owner has a farm outside the city where he grows his own wine, olives and vegetables and his wifes family has a fish stand where they get the fresh catch daily. Even the cheese is made right outside of the city at his elderly neighbors house! You have to make reservations (the hotel can do it for you - even though the place is small it has a really good reputation) and the owner and his wife will serve all the food before the show begins. It feels like you're visiting close friends and they're playing music for you in their living room, but the atmosphere couldn't be more traditional and his wife has a very beautiful voice.
While all of Lisbon is dotted with adorable restaurants, the Barrio Alto and city center are extremely over priced and touristy. For the real good finds head to Alfama. The salt cod is a must (bacalhau) and of course the pastry shops. You'll have to try port wine and the local whites while you're there -- but beware, the ports are so strong and very pungent!
Truthfully, even with a week in Lisbon, I felt like the city was unconquerable because of the expansive size and wealth of tourist attractions. I am generally all for saving money and utilizing the public transportation ..but a hop on hop off tour was the best investment I ever made. There are more unique museums, monuments, castles, and neighborhoods then you can imagine and with the hop on hop off you can more easily navigate through the city and chose the few things you'd really like to spend your time on.
Tourist stops worth mentioning: St. Georges Castle, Belem Tower, Jeronimos Monastery, the museum that hosts the world's largest collection of royal carriages, design and fashion museum, world's 2nd largest aquarium, Parque Eduardo,
We did one day in Cascais, a small beach town about an hour north and if you can get there I 100% recommend it. We just added the trip to our hop on hop off 3 day pass, but there is a train that will take you right from Lisbon to the city center of Cascais in 45 minutes. From the drive along the cliffs to the pristine beaches and adorable boutiques ...I truthfully would take up permanent residence here if I could fish, cook, or really anything else useful for employment. Cascais bonus: If you go by bus you'll pass Estoril - which is home to Europe's largest casinos.