I live in a little up and coming neighborhood that has a great man street that is always filled with people walking up and down, plus it has great store fronts with awesome windows and architecture. There is one particular front that has this wonderful curved glass front with a fantastic carved old wooden door, and the inside is all pressed tin and beadboard. I would paint the bead board white, the top of the wall a kind of soft blue-green and leave the punched tin bright silver. I would find some antique or reproduction sideboards to store stuff/ display. Golden hardwood floors.
So that shop, combined with and old bakery/soda shop feel-lots of chrome and glass (a cleaning nightmare, but still!). Lots of pretty carnival and milk glass cake stands with clear covers. My staff would wear funny baking related t-shirts in all kinds of colors. (something like "I AM the muffin man!", "You deserve a cookie!" and "A muffin is a cupcake eaten before 9am"
I would sell everything from cookies, to cakes, cupcakes, pies, tarts, whole or by the slice. With a great coffee/ espresso machine and really good tea and a few little tables.
I would have 1/2 sized windows so that the folks could see part of what I was doing, or maybe a finishing table for the fancy stuff, but mostly everything would be in back. Like in Disney World- everything is behind the scenes-you just get the magic!
Sadly, there is already a fancy cake and a cupcake boutique on that street, so I will have to go the next little main street over. The store fronts are not as cute (but could be!!!!) but the rent is half and there is no competetion. Plus, it has more families that would be more likely to get larger orders, than just relying on foot traffic, which is an issue for the fancy cake lady on my main street. (her shop is tiny and she doesn't really have room for anything else-nobody really knows she is there)
I am planning on opening a shop next spring, so I have thought about this ALOT