Regarding your concern that getting a Starbucks would lead to "t-shirted coffee drinkers, slopping down the avenue":
I understand your concern. As a t-shirted coffee drinker, I confess: I enjoy a good slop down an avenue, many of them yours. Sometimes, after a long day at work, I savor slopping from South County road, past the church, and then I'll slop to the right, down Worth Ave.
Sometimes, my family will visit for a quick slop down Ocean Drive before hitting your Goodwill Boutique store. I also understand your concern about adding wi-fi. That will attract roving bands of ne'er-do-well, rapscallion, t-shirted, scamp-ish "people" with grooming issues. I agree.
Still, I don't think we do it without a certain amount of expected class and sophistication. Personally, I like to slop down the avenue with a higher-end drink, like a lite vanilla frap with whipped cream. It's class, all the way. It's not like having me enjoy my drink on your street lowers your property values.