Boraxo, you can always start your own private club. You can be as bigoted and arbitrary in banning anyone you want -- kids, blacks, gays, gay black kids, whomever you want.
However, if you choose to use a public facility (public, as in, not a private club), you'll just have to deal with the fact that not everyone is perfect.
Is it OK to complain about rowdy kids? YES
Is it OK to demand discrimination as a way to ward off undesirables? NO
Let's consider this for a moment.
Children are not a protected class.. they all races and creeds, and your analogy is little more than a red herring.
Is it discrimination when a strip club doesn't allow anyone under 21 in? Or when movies won't let anyone under 18 in to see a film? The totality of the world is not accessible to children because many places do not cater to children. There is no reason for them to be in a place geared towards adults, no matter if there is sexuality or merely the sale of a quiet, dignified respite.
Having children does not give one license to bring them wherever they want.
Let's not confuse "public" and "private" so readily. A restraunt or bar is a PRIVATE property..perhaps open to the public, but a private property either way. Same with lounges. The only truly public spaces are government buildings, the sidewalk, and the park.
There is altogether too much entitlement nowadays among parents. There was a time when you would never see a rug rat running around a brewhouse at 10 pm on a friday night. There was a time when you would never hear a baby crying during a screening of an R rated movie, or have to put up with one in a very very expensive restraunt with an adult menu.
There is a reason civilized places like Switzerland offer "No kids allowed" dining and train cars: KIDS ARE NOISY AND CAUSE A DISTURBANCE.