From extra leg room and priority boarding to inflight wi-fi, more airline travelers are willing to splurge out for extra comfort, with carriers keen to capitalize on a "large and restless" passenger base, a survey shows.
Demand for preferred seating is seeing the fastest growth among airlines' extra services, according to a survey published this week by travel research firm PhoCusWright, which polled around 1,600 leisure travelers in the United States.
Around one quarter of air passengers upgraded to a preferred seat or seat with extra legroom in 2012, compared with just 14 percent two years earlier, the survey showed.
"Air traveler consumption of ancillary offerings has risen significantly and steadily - faster than many airlines may have anticipated," wrote analysts at PhoCusWright.
In-flight meals, movies and priority boarding also saw substantial growth. For example, 40 percent of passengers surveyed purchased a meal or snack last year compared with 28 percent two years earlier.
"As airlines continue to roll out these services across their fleets - in particular onboard entertainment and wi-fi, the growth will only continue," the PhoCusWright analysts said.
One category that is gaining traction, particularly among those who travel more frequently, is airport lounge access, the survey showed. It said that 17 percent of travelers surveyed paid for lounge access compared with 9 percent two years ago.
Comparing demand between younger and older travelers, PhoCusWright, said the former are more willing to fork out extra cash for the add-ons.
For example, almost half of the travelers aged between 18-34 purchased food onboard, compared with just 29 percent of flyers aged 55 and older.
(Read More: More signs of sturdy growth: Consumer spending rises)
"Either unfamiliar with the glory days of full-service air travel, or simply more accepting of the enviable, they [younger travelers] are clearly more ready and willing to pay for the services their older counterparts came to expect in the base airfare," analysts at PhoCusWright said.
—By CNBC's Ansuya Harjani; Follow her on Twitter: @Ansuya_H