Dehner's and Vogel's are the big name brands, I don't think they make DerDau's anymore. Chuck Pinnell, formerly of Journeymen in Middleburg, used to make boots and shoes but I think he just does chaps and small leather work now.
Take a trip to Warrenton or Middleburg and go to one of the big tack stores there, find out which customs they carry and what the options are. MAKE SURE you get someone with experience to measure you; it's all about the measurements!
For a skinny, good lookin' show boot, go with 3/4 lined, cuff lined or unlined. (Fully lined is popular with foxhunters, for warmth, or for dressage riders who like a stiffer boot) You tend to get a better fit in a field boot and they're easier to get on and off. And personally, I like the ribbed rubber or Vibram soles. All leather soles wear more readily, and they're slick when your stirrup is wet.