You'll enjoy the museums and cafes in Kentron. You might want to make time for a stop at Republic Square or National Gallery of Armenia.
Shengavit might not have many top sights, but Hrazdan Stadium and Blue Mosque are two attractions nearby that you can check out.
Visitors to Nork-Marash like its mountain views and restaurants, and Yerevan TV Tower is a sight worth a stop.
While you're in Erebuni, take in top sights like Erebuni Museum and jump on the metro at David of Sassoun Station to see more of the city.
While visiting Malatia-Sebastia, you might make a stop by sights like Yerevan Park and Yerablur.