Next time you're in Vegas just chilling out, be sure to swing by Treasure Island Hotel. Each night at Sirens Cove, Google Map there is a FREE show from 7pm to 8:30pm (and other times). In Las Vegas a lot of things can cost you A LOT of money, but at least this show if free.
If you're a booked gusts at Treasure Island you get premiere seating for the shows but even if you're not, you can still watch. Check them out further at the official site: TI Pirate Show.