In our situation, we totally gage affection based on where we are, and how comfortable we feel being "out". In an anonymous, low lit restaurant we all three hold hands, cuddle, take turns giving each other a bite, a sip, a loving touch. On a walk we take turns holding hands, or walk three in a line if we're all feeling safe and open. Alternately, when we're in neighbourhoods where she feels more private, my husband and I hold hands and walk next to her. Sometimes they hold hands, kiss, hug and I get to admire and enjoy what a beautiful couple they make, and even get to watch other people enjoying looking at them too. When we're all together in a private place it's so touchy-feely-fantastic that we seem to not even really think about it, but being out and about is more about everyone feeling comfortable with outside eyes rather than our own.
Can I just say that I am in awe of RedPepper, her husband & Mono's relationship? SO cool.