You could do it as a once a month e-mail sent out to GCU members. They could be some of the usual ones from the former @Gamer magazine(that ended in May 2014 ) as yet another perk of being a GCU member. You could have the usual ones that became(unfortunately) a staple of the magazine's coupons towards the end like the extra percentage off pre-owned coupon.
As it stands the Gamer's Club offers that the company is releasing as of late are nowhere near on par with the offers we used to get.
Right now the ONLY Gamer's Club offer on the page I have bookmarked for it is 50% off a headset audio controller for the PS4: