TOD
A lot of Impressionism, moderate amounts of Cubism, and probably other styles of the late 19th / early 20th centuries are those I most immediately respond to. The earlier Hudson River School is a strong favorite, obviously influenced by my love of the geographical region.
Beyond that, I unashamedly love commercial art of the mid to late 20th century, especially as relates to movies, books, records, music, theater, etc.
As for having a feel for what any of it is worth ..... I'm ignorant, but am ever optimistic that anything I'd most want will be unaffordable.