I've done seven or eight duos in Montreal and New York...never out West.
My first was probably the best, since it was so exciting as a first-time experience and since one of the women involved probably could have opened a bottle of wine with her internal muscles. (Man, I will NEVER forget her...the agency told me she was "really tight," and they sure as heck weren't kidding).
I never got into the idea of watching the women "be together." Why watch when you can dive in? One thing that was distracting is the changing of condoms when switching off (which I enjoyed doing several times in each duo), but of course it is absolutely necessary for all concerned to protect themselves.
Was it what I expected? The first time, yes, since it was new and exciting and I was doing something all men fantasize about yet most never do. However, I never enjoyed another duo as much as that one. Part of it is that a couple times I was much more into one of the two women, and thus the other woman being there was just a distraction. One time in Montreal, the agency sent one woman who was a knockout and another who was, to me, not at all desirable. What to do? Had them both since I'd paid, but after a perfunctory roll with the undesirable one I spent most of the rest of the time with the other. Could have saved some money by only seeing one.
How best to engage two women? Well, watch a porn movie and use your imagination. I thought the best part was getting a BJ while getting a ball-sucking. The second best part: one woman cowgirl with the other on your face. Talk about sensory overload.
If you get a kisser in the deal, take her on while the other gives you a BJ. Now that's a tough feeling to beat.
One thing I liked was to have both women on hands and knees and to switch off on doggie style. Another thing you might like is to be doing the doggie with one while the other gets close behind you and rubs your chest and nipples. See how long you hold out when that happens.
I truly think every guy should try a duo sometime in his life. Hope this helps.