Marina Parque das Nações truly is a nice and welcoming marina! I spent there 2 nights last January. The staff is very friendly and helpful. Very good facilities!Don’t be surprised if you see a rare or weird bird around there… you’re in the Tagus estuary!
There’s lots of things to do and see around the marina, as it is surrounded by many leisure attractions like the Oceanarium (excellent for kids!) and close to Lisbon’s centre.
Also very good restaurants around there. Try the “mestre doce” and his codfish fried pastries… delicious!