We have had good experiences with AirBnB as well and I have some friends that really like VRBO.com, but the best thing we have discovered is doing home exchanges. We use a website called Homeexchange.com (costs little over $100/yr to join) that is set up like a dating website. Essentially, you use someone else's home while they use yours. You can search other states/cities/countries and even filter by only showing people who have stated that they want to come to your area. We are on our 4th exchange and really love it. The savings are great (spent a month in Paris couple summers ago without paying for a hotel at all) and having a whole house rather than a hotel room is incredibly luxurious. Finally, all of the people we have exchanged with have treated our home great and been very thoughful hosts.
There are a couple of caveats though....it can take some work and flexibility about finding someone from where you want to go that wants to come to where you live. There is no vetting process on the website, just setting up connections, so it does take some trust in humanity and being ok with relative strangers being in your home. There is also some extra house work involved in leaving you home guest ready when you go on a trip and cleaning up after yourself you vacate the home where you are visiting. However, if you are looking at couch surffing then these things probably won't bother you.
good luck!