Hospitality companies are trying to make the process of renting a vacation home simpler, more reliable and more like the process for reserving hotel rooms. Last month, three vacation rental booking companies, Mountain Reservations, Rooster.com and Mexican Destinations, combined their listings on one site, VacationRoost.com, offering customers amenities like check-in, cleaning services and the opportunity to book rentals with a credit card. Online travel agencies like Expedia and Orbitz have increased the vacation properties they list. Only about 10 percent of Americans booked a vacation rental in the last two years, according to data from PhoCusWright, but hospitality companies are hoping travelers will choose vacation homes over hotels in a down economy.