During my last 2 travels (a road trip in the USA and a motorcycle tour in Eastern Europe) I used Booking.com a lot. Using coaches and trains in North America or moving by motorbike from town to town in Romania and Hungary, finding where to sleep at night was one of my main concerns.
While I usually prefer campsites, in many countries hostels are so cheap (like 8€/night) that is almost stupid to plant a tend in a 10€/night camping. Many of the structures that you can find on Booking.com also have included breakfast, and this can help you save money for other activities in your trip.
Booking.com contacted me and sent me a referral link that you can use to book a structure and receive 15€ back! The good thing is that you can use it even if you already booked on Booking.com before!