Washington DC
Good day:
First let me congratulate you on your explorations.
Your question presuppose a relational frame work which by it's very premise creates a square peg or round hole situation.
The BDSM neighborhood has many houses. For example I am a heterosexual lifestyle New Guard Leather Male Dom-Top (yea I know a mouth full). Granted, I own an agency however I am not part of the Pro-Dom part of the neighborhood. There are those of us who live it as part of our lifestyle, however we do not practice it in a money making capacity.
So you know, there are conventions and seminars geared to Pro-Doms and then there are conventions, meetings (munches) and play parties geared to Lifestylers. As a general rule (not an absolute) we tend not to mix. Yes there are cross over points like the Crucible which I do frequent when I'm in town but on a national level those cross over points are not common. Nor am I ignoring the few Lifestylers who are also Pro-Doms.
I'm old school since I entered formal training as a Dom back in the 80's. I make a distinction between Dominance / submission and Sato-masochism (S/M). What you may call a Doming session is really Topping which is a function of S/M not D/s. Put it this way if you're restraining, flogging, caning, strapping etc.. it's Topping and it's actually S/M if you want to get technical.
A play scene can be sensual all the way up through the range of down right Sato-Masochistic hard edge play. Most practitioners be they Lifetylers or Pro-Dom generally find their comfort within that range of possibilities. Personally as a Top I like to work with a range of "bottoms" so I don't get into a performance and skills rut. I've had female bottoms who wanted soft and sensual and those who are what we call heavy bottoms, meaning serious pain lovers.
( and the cum so nicely too 
)
You asked about favorite Mistresses well that completely pre-supposes all Doms are Mistresses even Pros and not true. There are many Pro-Dom Masters in the MD DC area as well. Many bottoms when they find a top they connect with tend to stay with them because the ability to read another's overt and covert body responses during a scene accurately is part art and part learned. When you find someone who can do that for you, one tends to not want to mess with that. Again I'm not speaking in absolutes there are those who go from one experience to another, one top to another.
One of the things I used to teach when I did seminars at various BDSM conventions is the concept of "as you learn this, try not see everything as this or that." Yes, somethings in what we do are absolute. However, think of the learning exposure process as a "flow". Start at one point of view, then flow from the Pro Dom part of the neighborhood into the Lifestylers part, from S/ M bottoms to Dominant/submission and the subs, slave, Masters, Mistress area.
I've been at this about 26 years now and a lecturer for the last 7 and I'm still going and relearning and discovering things. I think that's why I'm currently teaching one of my escorts the "senual art" of what we do first.
GoodTimingMan - You have a valid point Lifestyle Dominants as a rule can't be clients by the nature of existence it's a different head space and the needs are different nor conducive.
The BDSM World et al is rather large and encompassing. It will take you some time before that simple fact hit's you and if you're humble enough you'll discover like I do every day how much I don't know.
With warmth and respect,
Lee Dreams ....
and no that's not my scene name.
DreamsEscortService.com