Everytime I've flown to Vegas, I wrap my cues in a towel and pack them in my luggage. Once there, I buy a throw away fabric case for the duration of the trip.
The other guys on my team opt to pack the cues like I do, but instead bring their empty case on the plane as a carry on.
All that said, my playing cue for those trips was very cheap compared to my current player. Odds are I won't fly with my new cue. I go to Vegas for the vaca and not overly concerned about marginal improvement in play a specific cue may provide.