I tend to use MUPs at hours in the morning where I have it all to myself...

"Wocka wocka!" says Fozzy the Fred!
Whenever I'm there during normal-use times, I tend to ride in "family friendly" mode, where every encounter is just one more interesting thing to experience. My favorite was a convoy of couples with baby strollers, of which there were 5, if I remember correctly. I too have learned not to "on your left!" to people, since they tend to take that as an instruction for THEM to move to the left half the time. Most of the time, they are really startled, so I'm afraid of causing a heart attack. So I just go glacially slow and pass them quietly at a speed where I can stop just by putting my foot down.