[onwardly]

As an entrepreneur in the travel space, my guess is that this move is primarily a PR move, and actual Bitcoin transactions aren't expected to move the needle in any substantial way.

If its primarily a PR move, the reason for starting with hotels is simple: Expedia, and all the OTAs (Online Travel Agency), make the VAST majority of their profit from hotel bookings* due to two factors:

1) Airlines pay extremely small commissions (starting with when Delta announced 15 years ago they wouldn't pay commissions on flights)

2) Hotels pay extremely high commissions, since unsold hotel rooms disappear as inventory the next day

Assuming the goal is PR, Expedia cares much more about getting consumers to think of Expedia as a place to book hotels than they do booking flights- thus they are "starting" with hotels.

*For example, in 2013 Priceline sold 270M hotel nights and 7M airline tickets. Of their $7B in revenue and $2B in profit, very very little came from airline ticket sales.