I've tried to use Sidestep, but without much success. Back in March, I needed tickets for a trip to Florida and Sidestep came up with the best combination of time and scheduling. When I clicked through to buy, I hit a series of roadblocks since the site kicks you over to a travel agency (which may or may not be captive). The process became increasingly byzantine and I finally called them to find out what I needed to do to complete the transaction. They told me to wait six hours for their computers to clear. By the time I tried again, the space was gone. Whether or not it was available when I first noticed it is something we'll never know. My sense is that Sidestep may give you a hint of what may be available, but I'd suggest that anyone trying to use their services confirm interesting possibilities independently. By contrast, Expedia, which I've used a number of times, has always been very easy and efficient.

Regards, Russell in Connecticut