Dennis Schaal

It is the beginning of year two for HomeAway within the Expedia portfolio, but rival Airbnb is also getting aggressive in its digital marketing of vacation rentals and Booking.com is no slouch, either. Perhaps to the chagrin of hotels, the vacation rental category is getting a ton of more exposure.

In 2008, Venere became Expedia's great hope in Europe to play catch-up and take on Booking.com's dominance. Whether it was a lack of execution or Booking.com's scale advantages being too imposing to overcome, that dynamic never came to fruition.

Hilton's decision to enroll in TripAdvisor Instant Booking while the chain is dedicating huge resources into convincing consumers to book direct on Hilton sites is an admission that it needs third-party distributors. TripAdvisor is a favored partner for the moment because it's cheaper than Expedia and the Priceline Group for the chain.

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In mid-2015 Kayak opted to go dark on U.S. TV and to put more investment into broadcast advertising in Europe. Companies have to make such hard choices sometimes. Kayak's Hafner claims, however, "the sky didn't fall" in the U.S., although one could surmise that Google Flights is "knock-knock-knockin' on heaven's door."

TripAdvisor CEO Stephen Kaufer has decided to make dramatic changes in the leadership of the company's attractions business, and that's not unusual for an acquiring company. Still, the move to import executives from the company's vacation rentals business to run a leading tours and activities business isn't exactly being welcomed with open arms by the rank and file.

Operators of online travel websites, if they know what they are doing, never finish testing and learning, and always consider their products works in progress. TripAdvisor officials are obviously in no hurry to settle Instant Booking into a consistent user interface that won't confuse the hell out of consumers because they want to perfect it first. Public company or not, they are in no rush despite investor impatience.

A next step for Rideways, if it really wanted to get out front, would be to transition to an on-demand service and start recruiting drivers, but being part of a public company, the Priceline Group, Rideways has to be very cautious about regulatory issues. That's sort of like trying to be a disruptor -- or a hedge against disruption -- with one hand tied behind your back.

A prudent strategy for Airbnb might be to initially partner with an online travel agency in an affiliate relationship so it can access flights for its customers. In that way, Airbnb could test whether its users want to book flights on the site without taking the big risks involved in making a large acquisition, which could always come later.

TripAdvisor has been struggling but it is a testament to its continued power as a marketing vehicle that Expedia Inc. felt compelled to participate in TripAdvisor Instant Booking even though Expedia controls its own TripAdvisor wannabe. It's called Trivago. A newly anointed public company, Trivago's growth could one day be an Expedia hedge against TripAdvisor's clout, although Trivago isn't there yet.