Boot fits are such a varied and personal thing, I don't think you're going to find a shop for people with larger calves. I think you need to pay attention to the type of boots that are likely to fit you. For example, boots that go to the knee or half way up the calf may not fit you, espcially ones with zips or buckles. I'd say you'd definitely want to try the scrunched top pull-on boots and ones with flexible lace-up tops.
It also depends on the size of your ankle comparatively. If your ankle is much skinnier than your calf, you will find yourself in shoes which are too loose at the ankle.
I'd say boots slightly higher than the ankle might be better than say, knee high. It also depends if you're going for girly girly or chunky punk boots. Chunky punk boots are likely to come with a more uniformly large ankle/calf width, wheras girly stilleto heels are likely to be very narrow at the ankle. I think you might be able to find something in between, but range of styles is a limiting factor.
Stay away from anything that will look really tight, shiny leather or vinyl, go for casual loose boots.