Visit to Spain in November 2012 (Abu Dhabi)

Greeting to all of my friends;
I need your help... !!!!???? I am planning to visit Spain this Nov. Protected content 16 days (work and pleasure). My trip will start in Barcelona. I would like to know where to stay and go in Barcelona and if traveling by air or train or sea inside Spain is easy and fun? If yes what places or cities I should visit and how much time should I spend in each city. Also, how is the weather in November…Should I take my winter gear or pack light. I welcome all the ideas and suggestions you all can provide ASAP so I can start plan for my reservation

Regards
Ed