Hmm...I'm not sure what type of cookies you're making, but I would never use melted butter in the cookies I make with heavy butter bases (butter, sugar, peanut-butter, or choc-chip, for instance). The butter needs to be mostly firm to get a good consistency when you cream it with the sugar. (I don't even soften it in the microwave.)
Melted butter will result in an extremely flat cookie (think paper flat) --after you deal with the runny dough and trying to get that laid out on the cookie sheet properly...When I'm baking, usually I'll cube my butter (and it has to be full-on 100% butter -- margarine or blends just aren't the same) right out of the fridge first and throw it into the Kitchen-Aid while I prep the rest of my ingredients. By the time I'm ready to cream the butter with the sugar and vanilla, it's usually perfect -- not rock hard, but not soft either.
As for cookie-spread --and this goes along with the idea of not using melted-butter in your recipe -- the colder the dough, the less spread you'll have. Throwing the dough in the fridge (in the stainless Kitchen-Aid bowl) in between batches, and even for about 10 minutes before the first batch will help with getting firmer, less flat cookies.