Hotwire's 'disclaimer' that they will not make any substitutions or changes for an unused booking is unethical, IMO. People have various reasons why they need to change their booking dates, and Hotwire is raking in the money for unused services.
They also claim that they are giving you a 'preferred rate', which is marginal, if any, and then, you see a real 'good deal' to your destination in your e-maill inbox within a week.
We had to re-book our trip to Louisiana, and were turned down flat when asked if we could transfer the use of a rental car that we already PAID FOR.
There should be a law against these practices with on-line booking agencies. They are supposed to be there for our convenience.
We live in an age where every dollar counts! No one can afford to sacrifice money paid for an unused service!