Go west or go east from Managua? West is the UNESCO sites and volcanoes around León, east is Granada, Masaya, the islands of Lake Nicaragua, and more volcanoes.
I am greedy and though only with 2 days, I eventually compromised by visiting both. I loved the energy of university town León and volcano boarding was a great treat.
I got to Granada and it was a snooze. It has the typical churches and squares, and FSLN remnants, but it seemed a ghost town except for the tourists passing the hours in cafes. It seemed a museum piece rather than a vibrant town. I did not have time for the islands that many rave about, trusting tight schedules to irregular ferries is a poor idea.
Masaya is a grimy, busy town. I am not into markets other than food markets, and the heralded market there is lots of junky tourist bric-a-brac.
Volcan Masaya is great, though, you drive right up, collecting a hardhat on the way and up at the crater you are instructed to “Park Your Car Facing Exit.” I enjoyed joking with the guard whose head is so hard he says in his toothy grin, that he does not need a helmet.
And the nearby Fortoleza Coyotepe is great fun to drive with a manual up the steep, twisting single-lane road.
Since Managua Airport is east of the city, Masaya, the volcano and the fort can be reached in about an hour without having to navigate through Managua, and is on the way to the beaches of San Juan del Sur. León is a solid 2 hours and requires that Managua passage.
Yes Granada is a very laid back town. But it is also a very old town. spent lots of days there doing nothing.