Lower Gwladys for the best atmosphere, Upper Bullens for the best view imo. Though the games may end up having poor atmospheres and there are some pillars in the Upper Bullens.
Game day, ignore any advice about staying in town/the city centre drinking before kick off. I'd get to Goodison early and collect your ticket so you don't get caught in any ques just before kick off.
Visit St Lukes Church, the fan park maybe even the blue base, loads of pubs that will be chocker with blues before and after the game. You'll get to see everything the city centre has to offer whilst staying over, and wont have many chances if any to experience match day at Goodison with the move to BMD.