This 800-series 737NG is operated by Canada's second largest airline, WestJet Airlines.

The aircraft pictured is one of more than 20 in service w/ at least 10 still on order. The airline also operates the 737-600 and 737-700, plus, it will operate the Dash 8 Q400 NextGen under WestJet Encore.

(I have yet to see a 600-series from the airline here at McCarran)