Thoughts between Majestic, Fuster and Olivia Balmes. Concerned Balmes is a scene on the weekends. Have been multiple times, and looking for a good pool area.
Try the Hilton Diagonal Mar. We stayed there last year. Great outdoor rooftop pool and deck.
K+K Hotel overlooking Parc de la Ciutadella. Small pool and lovely terrace. http://www.kkhotels.com/en/hotels/barcelona/barcelona/photogallery/
Rated #8 on TA http://www.tripadvisor.com.au/Hotel_Review-g187497-d2558794-Reviews-K_K_Hotel_Picasso-Barcelona_Catalonia.html