Unfortnately, the only promotion current running at the Hard Rock is "Progressive High Hands".
The Diamond Royal is over $2000. A few of the straight flushes are also over $1000, but these get reset when they are hit, so you'll need to check with the poker room for current values.
Progressive High Hand
There is a progressive jackpot separately for each individual four of a kind, each straight flush and each royal flush by suit (a total of 26 progressives). Each progressive can be hit once per day. At 4PM, new progressive amount are posted (those hit the previous day are reset). In order to qualify for the progressive, both cards must play, there must be $15 in the pot and there must be a showdow. So, if you flop quads, you really can't bet because if everyone folds you don't qualify, which leads to some strange betting.
Money is added to each progressive each day (and there is a base amount for those hit that were hit the previous session).
Other than the usualy complimentary beverages, the only other player perk is a five dollar food voucher awarded after two hours of play. Only one of these can be earned a day, and they expire after twenty-four hours. Also, the voucher can only be used at the "24/7" coffee shop (which doesn't even open Mon-Thu until 9PM, and the buffet (so it is basically a $5 discount). However, there is a poker room menu that you can order from and have food delivered to the table. Most items are around $10, and you can just pay the difference (or save a coupon from the day before to add to the current one to get $10 in comps, which covers most items).