If you want to add a few miles, first casino from Ontario is San Manuel is located in Highland, CA. From Ontario, East on 10, North on 215, East on 30/330 to second Highland Ave exit. Turn left off freeway and follow signs, past Taco Bell/Chevron station, turn left at intersection with gas station and Food 4 Less.

Get back on 30/330 east bound to connect back with 10 east bound. Just past the 60 connector is 74 (I think) to San Jacinto. Soboba is a little harder to find. About 15-20 minutes south of 10.

Get back on 10 east bound 15-20 minutes to Cabazon exit and Casino Morongo is on the north side of the 10 freeway.

Get back on 10 east bound 15 minutes to Palm Springs exit. Spa is in downtown. Or continue 45 minutes east to Agua Caliente, on south side of 10 freeway on Bob Hope Drive.

Get back on 10 east bound about 20-30 minutes is Fantasy Springs on north side of Freeway. Next couple exits east is Spotlight 29.

For a real adventure you can visit Anza, CA and see Cahuilla Creek Casino, a real small Indian reservation in the middle of nowhere.

Come back to 215 south and go 1-1.5 hour south to the San Diego County border. Lake Elsinore Card Room in Lake Elsinore, Pechanga in Temecula, and Pala, Pauma, Vista Valley, and Rincon near Pala.

Since you're in San Diego County you can add a couple hours and go to Barona, Sycuan, Viejas, and Golden Acorn.