For me the main reason to visit Verona is its marvelous mediaeval churches. I would recommend buying the Verona Card which allows you entry to the five top churches - all of which deserve a visit - as well as to the Roman Arena and Castelvecchio (the Scaglier Palace with a picture gallery). There is also a Roman theatre where plays are performed (don't confuse it with the Arena which is an amphitheatre). Near the theatre there is a nice small archeological museum.