Possibly the best promo out there now is the Silverton earn 500 points on Tues/Wed and get a $20 comp. Silverton’s VP is garbage, but there’s still some 8/5 Bonus (whee!) left (much like Tuscany or the M, those are the only machines in the joint that are playable, and then only in conjunction with a promotion). As the LVA mentions, your EV is about -$4 on $500 worth of action, making your expected value $16. One mildly redeeming feature about 8/5 Bonus (or 9/6 JOB, if available) as a points-accumulation tool for promos is that you will rarely get stomped through the floor. If you, by contrast, were playing something like 9/6 Double Double Bonus, you could easily lose $100+ while running that $500 through–which would be a psychological blow and would probably add a bad taste to the “free” meal that you had thereby earned.
The above relates to a subject I’ve mentioned before–the volatility of promo-chasing. In certain situations, you might want to pick a game with an inherently lower EV than the nominally best game available, but having lower volatility. A “hit-and-run” promo wherein you have to put through a modest amount of coin-in would be a good example.
Likewise, if you’re playing to earn some kind of gift, you need to not only figure the EV of the amount of play needed (and these days, you’ll only be earning those gifts by playing -EV games), but the true value of the gift/prize (how much would you have paid for it?), as well as the opportunity cost (if it takes you an hour to go to the casino, play the required amount, and redeem the prize, could you have spent that hour doing something else as or more productive, including playing a +EV game instead?)