Since "most" of lv is now owned by either mgm group or harrahs, it is interesting to compare their comp systems.
With harrahs, as you play slots (with your total rewards card in the machine) you accumulate base and rewards points; the latter can be used as cash toward eating in resturants (or even paying your hotel bill)--this is yours to use as you want.
mgm system is a "secret" comp system. If you want to get comped for a buffet, say, you go to the players club desk, they look at a computer screen (which you don't see) and based on your play can acceed to your request (or deny it.) In some sense, under this system, you feel like you are "begging" for a hand-out. On some occassions this system can work in your favor--but you really don't know what the rules are.