Which site to go with depends on what you want out of an experience. Both, and others such as the long-running vrbo.com (Vacation Rentals by Owner), offer an alternative to traditional hotels and a chance to dive into life as a local. In San Francisco, where Airbnb is based, the company recently launched "local lounges," established coffee shops where Airbnb guests can stop in to get a welcome and a travel guide.
On Airbnb, the focus is on the accommodation. The best listings will have plenty of photos and reviews from other users. Couchsurfing profiles, meanwhile, read more like dating sites (though the rules bar using the site as such) or a place to find random new friends. You add photos and other users as friends. You can flesh out your profile to include musical tastes and life philosophy (my husband "would much rather try something stupid, dangerous or bad for me than risk feeling regret over missing out on something at the end of the line." I married the right man).
Since there are no commercial transactions on Couchsurfing, the site uses other ways to verify that people are who they say they are. Paying $25 will match the name you put on the site with the name you use with your bank. If you do that, you'll get the words "identity checked" next to your profile. Couchsurfing then mails a postcard with a special code to the address you provided. Once you enter the code on the website, you are "verified." We were more likely to accept verified guests, though it wasn't a requirement.
I also connected my Facebook account with my Airbnb and Couchsurfing profiles and checked out the Facebook pages of potential hosts and guests. We even used some interest-based filters to vet potential Couchsurfing guests. For example, having been to the annual Burning Man event in Nevada will likely get you in our door, while other hosts might automatically disqualify you for that.
The more you use the sites, the more friends and reviews you get from other users, which further serves to ensure trust. It's a bit like eBay, and how your cred improves the more transactions you do and do well.
The rest comes down to gut feelings. We made it clear to potential guests that we live in a small apartment and that they'd be sleeping on our fold-out futon in a living room with no doors, possibly with one or two cats on top of them. On weekends, we stroll around the city to explore new and old sights, scenes and tastes.
If that's not your cup of tea, the Hilton in Times Square might be a better bet. I won't forgo hotels now that I've tried out Couchsurfing and Airbnb, but it's good to know the options are out there. It certainly makes travel — and staying home— more interesting.
Follow Barbara Ortutay on Twitter at https://twitter.com/BarbaraOrtutay