As you know the sister casinos (Fiesta and Texas Station) are at the corner of N. Rancho and W. Lake Mead.

I do not know of any connection to a casino downtown, but you might try giving the Palace Station (on West Sahara next to the 15) at 800-634-3101, see if they have a shuttle to the Texas Station and then take a cab to the Palace Station. I know there are buses running on Rancho, but not from where.