Aggressively priced discounted first class fares, combined with the TODs. Sometimes, the upcharge over economy is negligible at booking if you care to check. I bought a high fare class ticket in coach to LAS a few weeks ago and paid $11 to upgrade to first, a few days before departure.

Also, for me, 1K again in 2015. PQDs were not an issue due to last minute bookings and outrageous fares, especially on short domestic routes. Other people's money.