ever since George Howell sold Coffee Connection to Starbucks, there are very few quality coffeehouses in Boston area. There are many busy coffeehouses, but I think only a handful are decent, and Simon's at 1736 Mass ave Cambridge, MA is truly good. On Newbury Street, and Boylston Street, I know Espresso Royale does pretty well because I have one of their ex-barista working for me, but you are looking at pretty steep rent, so you need to ask yourself how can you take business away from Starbucks, Espresso Royale, and other shops? I think in that area your shops outside apparance, outdoor seating, shop design and atmosphere are probably more important than pulling the best espresso shot per se. Best of luck.