I have been on several and actually met my husband on one. When we lived in Chicago, there was a Catholic retreat house that hosted retreats all year 'round. They weren't specifically Catholic; they did all sorts of topics from couples retreats to spiritual renewal through walking (they had a labyrinth...walking those is a very meditative experience). Sadly, it got bought by the county and closed last year. But if you search online, you can probably find out whether you have any retreat houses in your area.