Given your circumstances and needs, I'd get a navy hopsack as my next jacket. That can serve as a staple navy into the autumn, when it's too cool for fresco.
I toyed with a blazersuit for awhile, but realized that there aren't many occasions when I want that "in-between" status. Either I'm in circumstances where I want a suit in a suiting fabric and more formal details, or I want a jacket that stands unmistakably on its own.
Blazersuits look great in the IG/blogosphere, though, so if you can wear whatever you want without too much concern for context, go for it!