I don't know about this Statons Bucks thing, but we have also been denied using any points less than the full amount to pay for a room at GVR. I wouldn't go converting my points to Stations Bucks at GVR unless I was certain you could use them in that manner there.
These promos can be maddening. We just got back from Santa Fe Station, where we had coupon books they used to give out upon check in. These coupons have no expiration date, but last time my husband was there he had some trouble using them. So we checked with the nice lady at the front desk upon check-in, to see if we needed to just toss them. She said no, they were still usable, that it had even come up in a recent meeting and the manager told them they must honor the coupons. We had a 5x points we wanted to use in particular, so she called the slot club and they confirmed the coupons were still good. We turned it in without any problems and got our 5x points for that day on my husband's card. The next day I went back to the slot club to turn in the point multiplier coupon on my card. The lady at the booth ripped the coupon up in my face and told me they were no longer valid, even though I tried to explain what happened just the day before and even gave her names of employees. She didn't even want to hear me. On the third day of our stay, my husband decided to give it one last shot. This time the lady on duty at the slot club told us that any multiplier on the coupon would have been automatically uploaded to the kiosk (this has NEVER been the case with this coupon). We just looked at each other and walked away. Three different days, different employees, different answers. And one very rude employee that didn't even respect me enough to listen.