If you're looking for authentic Mexican food while in Vegas, look to Casa Don Juan. We went to Dos Caminos in Palazzo the day before and I would pick CDJ in a heartbeat over Dos Caminos.
First of all, the host told us to wait 2 1/2 minutes. As a joke, I timed him. We were seated in 2 minutes 27 seconds. HAHA!! Seriously.
They give you free chips and salsa...and bean dip! Bonus! The guacamole is a must have. So fresh.
Everything is good here. Carnitas, machaca, chorizo, carne asada. Everything.
Service was excellent even though they were packed.