A place to sleep is the most expensive requirement human beings have. We get better value on our houses and apartments at home because we're staying long term. Short term accommodations on the road tend to be much more expensive. Most people think only of hotels, but there are many more choices than that. If you're looking for a vacation rental to stay in during your road trip, you might want to look at some other options when it comes time to book accommodations.
Hotels and Motels
Often the nicest places you can book into on your road trips are hotels. In a hotel you're guaranteed your own private room with a washroom. There will likely also be free toiletries such as soap and shampoo and probably even a free continental breakfast depending on the quality of the hotel. Motels are slightly more basic, with each room having its own exterior door, which makes it more convenient for travelers who are living out of their cars.
Bed and Breakfasts
If you're looking to interact a little more with the locals and save some money, too, you might consider stopping over at a guest house or bed & breakfast. In a guest house you will have your own room but you may have to share a bathroom. The number of guests will be small, as B&Bs tend to be private homes, and the proprietor will make you breakfast in the morning and give you any information you need on sightseeing in the city.
If you're thinking of staying a little longer (generally a week or more), you'll find the best value for your money lies in renting an apartment or condo. Most water vacation rentals take the form of cottages while in other places rentals might be condos in a complex. In a rental you'll have your own kitchen, dining room, and living room, so you get more space and can save money by cooking your own meals.
Often a Puerto Vallarta vacation rental for example, is beyond the budget of student travelers and backpackers so a hostel would be the best choice. Hostels offer a variety of accommodations, from a single bunk in a dormitory to a private room, but generally involve lots of sharing in exchange for cheap rates. Hostels are great places to meet other travelers.
Sometimes the best value for your money, however, is to rent a campsite. If you own a trailer, RV, or even a tent, you can rent a spot at a campground relatively cheaply. You won't find them convenient to cities but in towns and wilderness areas they are abundant. Most campsites have toilet, water, and cooking facilities and many have general stores and electricity. Try going to a large popular camping website like KOA.com for campsite reservation information.