This promo runs every day throughout the month of July. Earning 100 points gets you $10 in free play. There are basically two reasonable options here:
First of all, one surprising element is that you keep your points--the free play is over and above the comps and free play you normally earn. Cash and comps @ $8/point = 0.9375%. Cash and comps @ $16/point = 0.4688%. (These amounts are 2/3 comps and 1/3 free play.)
1) Play 10/7 Double Bonus. This game returns 100.17%. It takes $1600 coin-in on this game to earn 100 points. This equates to an 0.6125% bonus, making the overall return 100.7825%. That plus the 0.4688% gives you (rounded) a total return of 101.4%.
2) Play 9/6 JOB. The game returns 99.54%. It takes $800 coin-in on this game to earn 100 points. This equates to a 1.25% bonus, making the overall return 100.79%. Add to that the 0.9375% and you get a total return of 101.73% (rounded).
So, somewhat counterintuitively, the worse of the two games, JOB, actually provides a better return. However, there's another wrinkle to consider. There's a limit of 2,000 points you can earn for this promo in one month. So you would be looking at $32,000 coin-in if you played 10/7, but only $16,000 at JOB. Multiply it out and you can expect to earn about $450 playing 10/7 to the max of the promo, or about $280 playing JOB. Of course, there's less risk as well as less variance playing the JOB option, as you only have to (or can) play half as much.
A further consideration is that there are many more 9/6 JOB than 10/7 DB available. Finally, it's a lot easier to play perfect JOB than it is to play perfect DB.
