Seltzer + lime is a fairly standard option.

Bonus, it looks like an alcoholic drink if you’re a woman and don’t want to give the idea that you might be pregnant, which is an issue which women trying to grow in corporate situations face at events, when in reality they simply don’t like drinking and/or don’t want to be around a bunch of men getting hammered who may potentially have sway over their careers.

That's actually a really good idea. I'm not a woman so there's not much risk of people thinking I'm pregnant, but I could see some kind of lime seltzer being good and people could assume it's a gin and tonic or something.

I might steal this.

There are quite a few decent alcohol free beers these days although they’re not sugar free.

I joke with bartenders and ask for fermented sky juice (good ol' water). They usually understand and smile.

And yes, perrier or just soda with lime is also perfectly acceptable too.