I've been going to Hackers and Founders off and on for the last six months and always enjoyed myself. Jonathan does a great job of making it a welcoming and friendly environment. Bring your side project, or help give feedback to other people about their side project. It's a great way to get an outside perspective on technology (that is, apart from the people you normally work/socialize with).
But I've never been, mostly due to being dependent on others for rides.