Jardins and Itaim are probably the best locations for a gringo. Jardins is a walkable area, Itaim not so much although some might desagree.

Campinas might be an alternate location as Azul airlines gets you to whole country out of Viracopos aiport ( my base for internal flights ).

S. Paulo hotel prices that are already extremely high will surely go up to stratosfere during WC14.

There´s a site for long term rentals ( in portuguese only ): http://www.aluguetemporada.com.br/

PM if you need more info.