I'm female, and like the poster above: I play it all.
It all depends on what I want out of a game I'm playing. When I want to test something out, or figure out new gameplay (e.g. with each expansion), I'll usually roll only one sim (sometimes two if I want to speed things up and am confident I can keep track of it all). When I got what I wanted they sometimes evolve into a family, but not always. Then I also play games with just roommates, it's a lot of fun (and craziness) to have 2+ sims under one roof who're all trying to find their way out of that house. When I play families I tend to start with one sim, but I'll usually make a sim of the opposite sex myself and move them into town, so I get just the looks, traits, and LTW I want. That way I can play from one sim to a lot (I love toddlers!), and sometimes even multiple generations. Elders are what I play least with, not entirely sure why, but I tend to switch to a new YA (kid, townie, or otherwise) when all the raising is complete.