Every bra in my collection (aside from two) are the Exxtreme Cleavage demi bra from Frederick's. They are lightly padded with the option to put in the extra lift padding. They have under-wires which are great for support. These are some of the few bras I haven't had a problem with the wire poking me somewhere.
I have always preferred some padding for hiding the nipples. From what I can remember, high school class rooms are kept COLD, and having some guy make a comment about headlights or having to sit with you arms crossed for almost an hour while trying to pay attention, is not the most enjoyable thing or the easiest in the world.
I have been thinking about getting a nice non-padded no under-wire bra for sleeping in. I have been noticing they ache when I get up in the morning. I generally sleep on my side with a soft down pillow in between them but I often wake up on my back. Gravity that way can't be helping