1. Two programs
2.
Originally Posted by
goalie
2-upgrades but followed closely by "being taken care of" if need be, choice of seating with no restrictions and priority boarding
Originally Posted by
pinniped
(2) General ability to obtain mediocre (instead of horrific) customer service from the airline. All other perks - upgrades, lounge, bonus miles, etc. - are secondary.
Like
goalie and
pinniped pointed out, a better shot at being protected/cared for in the event of IROPS, combined with shorter lines, shorter phone hold times, and other touches that improve the customer service experience. (bypassing a 100 pax long check-in line to get in the one person long elite line, then going to the lounce and spending that extra hour relaxing makes the experience almost civilized).
Upgrades, priority boarding, etc. are a subset of this answer, as are most of the other perks.
3. no
4. no