When many people think of the Upper East Side, they think of a quiet, tree-lined urban expanse filled with posh residents and purebred dogs. There’s some reality behind the neighborhood’s old-money image: The blocks between Park and Fifth avenues are home to some of Manhattan’s wealthiest residents, many of whom dwell in stately co-ops or sleek new condos overseen by stiffly collared doormen. But there’s a lot more than old money on the Upper East Side. The Museum Mile throngs with tourists, street artists, and lovers of the arts, drawn to its abundance of high culture. And the eastern side of the neighborhood, toward Yorkville, exhibits a less rarefied character. Second Avenue is home to sports bars, Irish pubs, and some excellent restaurants. A trendy renaissance is in the offing here, sparked by young professionals drawn by some surprisingly good housing prices (for Manhattan). The avenues and commerce-lined thoroughfares can be hectic, but many streets on the Upper East Side are blessedly quiet — just one more way in which this oft-stereotyped neighborhood can be a surprise.