Having breakfast looking out across the city is a great way to start the day especially when the sun is out! Accessing the apartment is easy but if you're walking back from town be prepared for an uphill hike, you can easily get a tram instead which stops nearby. Taxis in Lisbon are also very reasonable so you can always do that either.
Lisbon is a great city and we will no doubt be back to visit, I definitely recommend going down along the sea front by the palace, it's a really nice area.