I've always had a slight fetish about sessioning with women near my own age. With much younger women, it's a little easier to idealize or objectify her. With a woman my age, she's a full on peer of mine, someone who has lived the same life experiences as me. For some reason, the thought is sort of extra humiliating.

I love femdom with women of every age, but I find I have a slight extra bit of excitement with women close to my own age (for the reasons above) and very young women (20-24-ish range, because the age difference in itself is so stark)