Together with our 3 kids we had a very pleasant stay in Helen's appartment. It's perfectly located on top of the castle hill. Don't be afraid of the stairs you have to climb, there's two elevators which overcome 90% of the height difference to Baixa-Chiado. And just in case it's doable on foot anyway. The immediate area currently seems to be rejuvenated, which is nice and there's nevertheless almost no nuisance due to construction works. Helena is a very nice and responsive host. Fortunately two of our favourite places were just a short walk away: Chapitô à Mesa which combines good food with performing arts and Tu e Eu 2 (the "2" is important) where Maria, the cook, will serve you the best traditional food you can get in Lisbon.