Floating beds, craft bars, and rock ’n’ roll décor are just some of the amenities at Boston’s newest crop of boutique hotels. Thanks to a robust economy, Boston’s hospitality market is booming, with average room rates and occupancy reaching new highs. Boutiques make up roughly half the hotels slated to open in 2015 and 2016 in Boston and Cambridge. “The boutique market is being redefined,” says Thomas R. Engel, president of the T.R. Engel Group, a Boston-based hotel consulting firm. “It’s more about urban, infill locations appealing to younger, hipper audiences. The target customer is someone who looks to their hotel stay for an experience.” Here’s a closer look at a trio of Boston’s boutique hotels, which offer a sense of playfulness, novelty, and pleasant surprises.