Kayak and Hipmunk
As I mentioned when discussing flights, Kayak and Hipmunk are meta search engines that combine results from multiple other sites like online travel agencies and brand websites. They’re good, basic places to search for a hotel and usually among the first places I head to get a sense of the going rate.

Google Hotel Finder
One of the nice features about it is that you can actually draw an arbitrary shape around the area you want to search. For example, if you were looking at Honolulu, Kayak’s radius feature could be a annoying if you only want to stay in one long and narrow strip of Waikiki. However, I find the rest of its interface to be unrefined and slow. You may want to include Google as an addition to Kayak and/or Hipmunk.

Orbitz and Expedia
I include these in one group because they’re basically the same. I like them better than Travelocity with one exception mentioned below. They tend to have good rates and good promotions, so unless I’m after hotel status I book with them.

Normally I don’t book through Travelocity because I dislike its user interface, but they have a great hotel search feature that Expedia and Orbitz don’t. After performing your search and choosing a property, you can look at a month-long calendar to find the best day to travel. This is also great for finding cheap nights for mattress runs.

If I’m not picky, I like Hotwire. I’ve always stayed in a nice hotel and paid a great rate. It will give you a price, some amenities, a star rating, and a general location. After you pay, they reveal the name. It’s even possible to determine, with some practice, which hotel they’re offering before you promise to pay.

Although similar to Hotwire, the difference is you offer a price and then a hotel decides whether to accept rather than the other way around. There are fewer possibilities for identifying the hotel in advance, so I generally avoid it if I know of any bad eggs in the area. Priceline also only guarantees bedding for two guests. However, sometimes the deals are better.

Costco Travel
I’ve often found Costco Travel to have great hotel + car packages and relatively cheap upgrade offers for tropical locations. Plus you can’t beat Costco’s customer service. However, hotel rooms are generally purchased at consolidator rates that DO NOT earn stay/night credit, so be sure to determine if this is a worthwhile tradeoff. Note: You must have a Costco membership, currently $55-110/year, but that includes all the $1 churros you can eat!

Pleasant Holidays
Another good online travel agency for Hawaii and other tropical destinations. This is one option where I would include air travel in the reservation. For flights to Hawaii, they usually book with United, and they will be treated like any other revenue flight. Sometimes in the summer they will pre-purchase more seats than they can sell and will have some great deals for mid-week travel.