I'm a long time (10+yrs) Couchsurfing.org member and organizer, and tried out the alternatives (BeWelcome, etc). Here's what I've learned about organizing in these communities:

1. You need a strong community.

It is absolutely essential that your membership is responsible for building a culture and reinforcing it. They need to set the standard for your site, and have the tools to keep it going. The community will create and organize events, get to know each other, police its members, form bonds, and welcome newcomers. This isn't easy, but not that hard either. The way it worked on Couchsurfing originally was forums and regular local get-togethers. Nothing fancy, just a regular old forum. But the functionality of the forum is necessary for the members to maintain the community. Having general discussions, pinning topics, 'leaders' of a particular regional community, sorting, advanced search, sub-forum hierarchy. Though unfortunately as with any forum, you'll also have to deal with spam.

2. If your website's features are shallow, so is your membership.

Couchsurfing went downhill once their forums went away, but it plummeted into hook-up culture once they added a feature to "find someone near you right now". It just turned into 50 dudes globbing onto the only chick in the area and mini groups forming around someone who's attractive. The profiles and hosting also turned into dudes only hosting chicks and vice versa. The loss of the community destroyed the entire point of the site, which was to meet travelers. If that's what you want then just have the "connect people nearby" feature, and people will just try to meet the hottest, coolest people they can. There's a market for that, but it's not the same as "meeting other travelers". The lack of community engagement also means people won't stay on your site for long, and it's the long-term membership that makes your site a reliable tool to use.

3. Enable the travel aspect.

Focus on the places, sights, food, music, culture, of each place. One of the most popular uses of Couchsurfing was just to ask locals "What's a good place to eat?" or "In what neighborhood should I stay?"

4. Use your website to shape the culture.

Provide a guide and examples for writing profiles. Add flair for common things people like, like a bowl of ramen, pair of skis, hiking boots, chess board, guitar. Let people personalize their pages with custom CSS/HTML/images - it allows people to express their individuality, which is a part of how people choose who they want to hang with. Suggest local get-togethers (pot-lucks, grabbing beers and hanging in the city square, easy hiking trails, city day tours, etc).

5. Enable the users to add value.

Allow them to add things like local attractions, events. This is another part of the core of your website ("finding local travelers") because people want to both know what to do locally, as well as find people to do it with. Make this super convenient and people will use it, and it will connect people.

6. Take safety reports and treat them seriously.

If people meet through your site, there's the risk of abuse (trust me, it happens). If you're a man running this site, you probably do not understand how at-risk women are when meeting a stranger, and how important safety is at keeping women on the site (let's face it, people will only use your site if there is a healthy mix of gender and sexuality, just like the real world). Community policing takes a lot of this burden off of you, but you still need to take reports and seriously investigate them, and ban people who cause trouble. Harm of an individual harms the community, which harms your site. I'm sure this will be somewhat "controversial", but it's important if you want people to trust your site.

All of that is a crap-ton of work. It may not be worth it for you to sink that much time and effort into your site. Without a community and the tools to develop it, I think your site may become a hook-up site like others before. Trust and community doesn't come easy, but when it works, it's beautiful. Good luck to you, dude!