Santiago, Chile
Los Adobes de Argomedo- This is a traditional Chilean restaurant that serves parrillada (miscellaneous barbecued meat) along with a great dinner show. The show features music and dance from different regions in Chile and has audience participation ;) . This is highly recommended for tourists. Every person we have taken there really enjoys it. Also, the Pascuenses dress very "authentically" which makes for nice eye candy ;)
Tip y Tap- If you have any German blood in you (and even if you don't) you will LOVE this place for lomitos (pork sandwiches), fries (Chile seems to have the best fries ever), and the beer they brew. Don't' pass this up and make sure you get avocado on your lomito.
Fuente Suiza- My husband argues that this place is better than Tip y Tap for lomitos but I give Tip y Tap the edge. Fuente Suiza is also a good place and the scene is a bit more "local".
Fritz is also a good place for lomitos and is located in the mall. Did I mention I love lomitos?
Pirque
Concha y Toro Vineyard- this is a great vineyard with beautiful grounds and has my favorite brand of Carmenere wine which I HIGHLY recommend.
La Vaquita Echa- This is a very cute and beautiful "traditional" Chilean restaurant that serves parrillada (miscellaneous barbecued meat). The backdrop of this restaurant is gorgeous. It is located very near Concha y Toro so a great place to go and eat before the vineyard so that you have food to soak up the wine.
Valparaiso
Cafe Turri- Take the incline up to Turri and enjoy a great lunch/dinner over a beautiful view of the ocean/ sea port.
Maitencillo/Zapallar
The beach town of Maitencillo is really cute. These smaller beach towns are great to walk around in and spend time completely relaxing, enjoying your own pace, enjoying the beautiful natural scenery, and having the priceless feeling of not having a care in the world. I have never been more relaxed in my entire life than I have here. You really can't go wrong at any of the local restaurants. The seafood could not get much more fresh unless you walk over to the ocean and catch it yourself (and actually by the time you were able to descale it the fisherman there would have you beat- you really should watch them cut up fish at the local market there- it's an art form).
The Zapallar beach is incredibly beautiful with it's surroundings- palm trees, pine trees, flowers, houses, raging ocean. Search google images for Zapallar and see what I mean. I highly recommend eating an empananda (a sort of pastry filled with various ingredients and baked or fried- baked shrimp and cheese is my favorite) and having a beer (I prefer Cristal) at the restaurant right on the beach.