Turn 1 is good. Its the high point of the track. You can see most of the track from that viewpoint.
Also, Turn 19, 15, and 12 are very good spots as well. A lot of crashes in turn 19 for some reason (maybe its the parts unlimited tent?).
IMO the paddock pass is not worth it. They have a paddock walk, which is mainly a roped off section maybe 30 feet from the garages. Thats pretty cool, but nothing to special. General Admission over Grand Stand Seating. Its a great track for General Admission.
If you can, gather on top of the mullet about an hour before the race. You can see the entire track and well worth the 20 buck vantage point.