The Red Rock Canyon tour was definitely the highlight of our Las Vegas trip. Curt our tour guide was incredibly knowledgeable about the canyon and a great guide with lots of stories about his outdoor experiences. Ask him about his first (and last) time sleeping outdoors "cowboy style".
We went in February. Be sure to bring a jacket, gloves and hat during this time of the year because it's cold and windy in the Canyon!
FYI, we booked this Pink Jeep Tour through http://www.alllasvegastours.com/