The far reaches of the upper deck (506-508, 556-558) are incredibly far away from the field, although the angle towards home plate are quite good for upper level seating. Sections 516-518 and 546-548 are similar to nearby Upper Level Infield seats and can be had for a fraction of the cost. 516-518 also offer a phenomenal view of the fireworks.
Though the last ten rows of the upper deck are under an overhang, much of the LF line will still be exposed to the sun during afternoon games. To avoid melting on a hot summer day, choose a seat on the first base side where shade begins forming first.