The Internet is absolutely the best place to do research for a hotel room. Whether you are researching a property by using sites like Tripadvisor or Frommer's, at some point you are going to want to book that hotel.
I typically start right at the hotel's web site and check the availability and rate for the date and accommodations I am interested in. Sometimes I learn something that makes me want to book directly with the hotel, such as wanting a specific type of accommodation.
Other times I'm just interested in a general area of a city (like when I went on a long weekend trip to Boston with our daughter) and any hotel meeting certain requirements, such as star rating and location, will suffice. In cases like that I check out a site like Hotels.com.
Besides providing great rates, Hotels.com has a Welcome Rewards program that can earn you a free night. I did some checking at other booking sites and I didn't see anything like this. (Hope someone will let me know if I'm wrong.) For someone who travels frequently, this can be a great deal.