Lisbon is a cracking city!
Mercado da Riberia, albeit very touristy, is worth a visit. The pig cheeks and mash in Cozinha Da Felicidade is worth the trip alone!
We really enjoyed a small restaurant called Floresta das Escadinhas. It's just off one of the main thoroughfares, only opens for lunch and has very few tourists. We had the best grilled sardines of our trip there.
Lisbon has some excellent wine bars, our favourites were Grapes & Bites, Artis and BA Wine Bar.
The Oceanarium is very good too if you want to do something a bit different.
If you fancy a trip to the sea-side I highly recommend Cascais. We did two weeks there last year and it was lovely. It's only about 25mins on the train from Lisbon.
Sintra is a similar train ride from Lisbon but was completely overrun with Chinese tourists with selfie sticks, I didn't enjoy the place at all.