There is a nearly-constant flow of steam, ash and gases coming from the Masaya Volcano, but that shouldn’t stop people from making the trip. Join a day tour from Managua and you’ll be treated to glimpses of a rare type of parakeet that can withstand the toxic gases near the crater. You may even be lucky enough to see some of the glowing magma that the volcano occasionally spits up.
Volcano was interesting. Masses market was enough for you to buy any souvenir you might want. Granada is a pretty colonial time, very much like Antigua in Guatemala.