Visas
Because the United States requires visas when Brazilians visit the United States, Brazil asks a reciprocal visa of US citizens traveling to Brazil. Generally, this is merely a formality, and the consulate is quite quick to provide the visas. Be aware that the visa must be used within 90 days of when you get it, so do not apply before February.
http://www.brazilhouston.org/ingles/jurisdic.htm shows which consulate gives visas for people from your state, and to get links to the paperwork you'll need to fill out.
Flights to Brazil
You will probably fly from the United States to São Paulo, with a connection to Florianópolis, a 45-minute flight. Your travel agent may be able to reserve a direct flight to Florianópolis, but if he or she can't, it is easy enough to fly to São Paulo and then connect to a national flight. Generally, Gol airlines is the least expensive option between São Paulo and Florianópolis. www.voegol.com.br
I have found that Continental Airlines generally has the best rates to São Paulo (www.continental.com), but if you want to make several flights within Brazil (to visit the Amazon, Salvador da Bahia, Iguaçu, etc), you may want to check out some of the deals offered by TAM (www.tam.com.br).
Getting around in Florianópolis
You can rent a car at the airport in Florianópolis at more or less the same rates that you would pay in the United States, and while you are on a tourist visa, you can use your US driver's license (this is the law, though if you get stopped by a police officer, you may find it difficult to convince him of this fact). Brazilian traffic is safer than it was a dozen years ago, but still more aggressive than drivers in Boston or New York. Local buses get you downtown relatively easily and taxis cost about what they do in the US.
Getting to Braço do Norte
We will rent a bus to take all of the guests on the beautiful two and a half hour drive from Florianópolis to Braço do Norte on Saturday, returning to Florianópolis on Sunday in time for the 4PM flights that connect to international flights in São Paulo. If you would like to drive to Braço do Norte, please be aware that there is a lot of construction on the road, but the whole trip is quite beautiful.
Braço do Norte is a very small town, and you won't need a car while there. If you want to visit the mountains nearby, though, you will need a car.