Exclusive Feature: Seems the mobile traveler has made a big impression on hotels, so much so that hotels are investing more in a mobile-optimized site.

Eighty-eight percent of hotel brands feature a mobile-optimized site and 75 percent of hotels have invested in brand-specific apps or capitalize on parent company iPhone and Android apps, according to the "Digital IQ Index: Hotels" study by New York-based L2 Think Tank.

The efforts are bigger than just a mobile-friendly web site, however. A separate survey from the Interactive Advertising Bureau and tech researcher Ovum shows 19% of US mobile marketers said they planned to up their mobile ad budgets by 50% or more in the next two years.

So why the focus on mobile, and why right now? Consider the shift in travel booking trends. More travelers are booking on-the-go, looking for travel inspiration at any moment, not just when they're sitting in front of their computer.

The problem, however, is that mobile booking sites have notoriously been complicated to maneuver.

The L2  study sites long wait-times, a cumbersome experience, and uncertain security as the main reason travelers don't use mobile sites to book travel - a missed opportunity for hotel brands hoping to fill last minute vacancies or inspire future travel plans.

To add a little fuel to the competitive fire, consumer-review site TripAdvisor recently announced the launch of its free mobile app that includes a number of new features, including access to the website's new Hotel Price Comparison, giving travelers an easy way to compare last-minute hotel prices and availability.

While you can't book directly with TripAdvisor, this new app is just one more step between a hotel and consumer direct booking.

So what does this all mean? If hotels want to compete for the always-on-the-go-traveler, mobile-optimized websites are a necessary investment. With more companies like TripAdvisor and Hotel Tonight jumping into the mobile meta search game, hotel brands will need to up their experience in order to keep customers coming back.

This is strictly an exclusive feature, reprints of this article in any shape or form without prior written approval from 4Hoteliers.com is not permitted.

Melanie Nayer is a hotel reviewer and expert on luxury travel around the world. She has covered all aspects of hotels including corporate restructures, re-branding initiatives, historical aspects and the best of the best in luxury hotels around the world.

Melanie writes a weekly exclusive column for 4Hoteliers.com