Questions about Rio grande do sol

Hi, I’ll be in Uruguay soon and coming back to Brazil for a second time. My question is should I fly directly into Porto Alegre and head north? The other option is take a bus from Uruguay and make my first stop Pelotas. Any advice is appreciated. Also where else / what to do in this state? I travelled north east Brazil 2 years ago. I’m wondering what the differences will be from south to the north of Brazil. Thanks!