Using the Query function on The Chip Guide, I find about 200 LE's issued in Nevada in 1997. Of those, I see these USAF 50th commemoratives:

Arizona Charlies
Ballys (5 of them)
Barcelona
Fiesta
Las Vegas Hilton
Imperial Palace

Sahara has only a handfull of LE's that have been loaded and this is not one of them.

The Query is dependent on the person loading the chip information to get both date of issue and type of chip (LE) correct for this to work, so there may be others. As far as I can tell, there's no way to include in the Query the event commemorated except for a predefined list of events (like Thanksgiving and Veterans Day). I just looked at the 5 screens of chips the Query found and picked out the USAF commems by eye.