We’ve always has had an affectionate place in our heart for Sonsie, the American-style Newbury Street bistro that will be celebrating its 15th anniversary in several weeks. Sure, we’re fond of memories. After all, we did throw our launch party at Sonsie 10 years ago. But our thing for Sonsie is about more than nostalgia. It’s tough enough for any nightspot, bar, or restaurant to keepits buzz going for more than a season or two. But if the crowds that gather for its intimate breakfasts, collegial lunches, and boisterous dinners and bar scene are any indication, Sonsie is as strong in the see-and-be-seen department today as it was when it opened its doors. And the kitchen (helmed by Bill Poirier) just keeps getting better, holding menu standards to a high level of consistency and innovating along seasonal and cultural lines. Sonsie owns an awesome spot on Boston’s social scene.