With the rise of the craft cocktail, sometimes it can feel as if the bubbles have been left behind, which is what makes the Riddler such an effervescent addition to the San Francisco scene. It’s a wine bar with a laser focus, offering more than 100 champagnes by the bottle and dozens of sparkling wines by the glass. The vibe is posh and playful inside the charming Hayes Valley building, which dates back to the 1800s. The ceilings were gold-leafed by the artist Caroline Lizarragara and the back bar is lined with vintage champagne buckets and glassware, including Zalto Burgundy stems and hand-cut Belarusian crystal coupes. Oh yes, and caviar. The menu is overflowing with it, from a generous scoop atop the signature tater tot waffles to an indulgent serving of Kaluga Hybrid on house-made potato chips with crème fraîche and chives.