Hi Alen, Montevideo is a great city to wander around, there's a ton of things just on the streets that you will stumble upon.
There are some really unique and beautiful colonial buildings and impressive street art all throughout the Palermo and Barrio Sur districts (usually on the streets parallel and closer to the Rambla). On Saturday and Sunday nights there will always be Candombe Comparsas (drumming groups) playing in the streets around those areas and they are very community oriented activities. When people hear the drums they come out of their houses with their children and either watch from doorways and balconies or join in the group as they march and dance throughout the streets. Its great fun.
There's also Montevideo Zoo which has rhinos, giraffes, lions and leopards and much more. Its open from Wednesday - Sunday from 9-7pm and its in Villa Dolores.
I'd say your kids would really enjoy the big Tristan Narvaja Flea Market. Every Sunday this place is bustling with life and they'll see vendors selling EVERYTHING from old toys and books to peacocks, Uruguayan crafts and fresh fruit and vegetables...its an interesting place!
Another thing that looks like a lot of fun are the paddle boats on the lake in Parque Rodo, I've been meaning to try them out for a long time but never got around to it!
Be sure to talk a long walk down the beautiful rambla (or maybe rent some bikes).
Hope you enjoy your visit!
For cultural events and shows check out this link when you're here: (its its Spanish though)
