Are you intending using your HB vouchers for lunch meals? Is that why the Cheyenne and Crocketts is out?
You still have a couple of options. You could use your HB vouchers at face value, and pay the difference, in Cafe Mickey, Walts, Silver Spur Steakhouse, or the Steakhouse in the Village. In these you can select from the a la carte menu, and a main course and drink may be enough for you, so it wouldn't necessarily cost a whole lot more than the face value of your voucher.
I've had a good meal at the Santa Fe evening buffet, and a horrible one. I think the reason was the time I went for dinner. First (horrible time) was at around 8pm, place was mobbed, food was cold by the time you got through the cashier and found a table etc. 2nd time was much much better, and excellent value for money. But I was there before the parks closed - around 6.30pm I think. I think it would be a similar experience at the Cheyenne buffet if you chose that.