110x isn't even that hard. It must be over 100x due the house edge. Everything below the 100x would allow users just to wager and loose the hotels edge and still end up with profit without any risk.
Made a
spreadsheet showcasing the statistics behind wagering on the max % chance to win which would be the easiest for most to clear the bonus.
Being forced to take a gamble at 40% chances is not great... but this also highlights something else about your site.
You offer a 200% first deposit bonus for Dash, which is actually pretty +ev for people who approach it this way.
A 32.26% chance to win 5.24235328 BTC, risking 1 BTC (in Dash)
.3226 * 4.24235328 + .6774 * (-1) = 0.6912 BTC expected profit.
Not sure about how well you might handle multiple accounts, but that bonus seems pretty appealing.