Finding a quality, well-made practical dress for under $100 is basically impossible but I think this one might fit the bill. I introduced The Fifth Label a few posts ago here, and didn't even realize this piece was also made by them but it stands to reason because their stuff is so good. A lightweight dress and a good pair of mules is the perfect outfit formula for strolling the streets of Venice. Since stripes are supposed to be popular this Fall (tbh not sure when they've ever really been considered "out") I'll totally be pairing this with a jean jacket and these boots I just purchased for Fashion Week.
This dress sold out on Shopbop, but I found it for you all here. I also linked a few similar options below.