To experience a spicy taste of what Carnaval feels like, you MUST see a samba school rehearsal. In the months leading up to February, samba schools like Tijuca get cooking to prepare for competition in the Carnaval Parades. Get yourself ready for hypotic drumbeats and spectacular dance routines. You may find yourself, as I did, stepping down off the curb and joining in! Don't worry if you have limited rhythm: everyone seems welcome.
Samba schools came into being between the 30's and 50's. Steeped in history, they also generate a wonderful feeling of community and camraderie. To see a five-year old girl trying out dance steps for the first time as her grandmother and uncles cheer her on is to realize the deep sense of continuity and spirituality provided by dancing in Brazilian culture, something Americans sadly miss.
Check with your hotel about arranging a trip to a samba school rehearsal.