I'm taking my first trip to Brazil for Carnival 2010 to celebrate my 40th birthday. I plan to spend 10-12 days there and split my time between Rio and Salvador/Bahia. I'm trying to decide whether to go to Salvador first and celebrate Carnival threre, then head to Rio to catch the winner's parade. Or, to celebrate Carnival in Rio first, then travel to Salvador/Bahia. I'll be traveling with a group of my female friends and we're looking to have fun. I'd like to get a feel for Carnival in both places, so I welcome any suggestions on how to best split my time.

Salvador then Rio most amazing although more touristy...

Before today would be the best time to reserve

for best hotels...

You can easily do both depending on how much energy you have. Feb 8-13 you spend in Salvador and Feb 14-19 you stay in Rio. Remember the special group parade in Rio for 2010 will be on Feb 14 & 15.

Have fun!

I agree with Lilica. But if you don't feel like travelling during carnival week, it's a good idea to spens Carnival in Salvador and then fly to Rio to enjoy the winners parade (Feb 20).
Anyway, there are a lot of carnival street parades ("blocos") on both cities before the carnival week. So be sure to come to Brazil some days in advance.
If you choose to go to the Special Group Carnival Parade in Rio, go only for ONE night. Although there are different groups parading sunday and monday, for tourists they look preety much the same.
Enjoy your trip!