I usually play rotations that include mostly YAs, but I have their family members and friends of other ages there too for variety. I like focusing on relationships and making things as dramatic as I can without getting too soap opera-ish. I make up backstories as I go along and add sims as I see fit.
My main save is an example of this, and pretty much every sim I post about on here is from that save (including the sim in my avi).
My other saves are legacies, playing with premade sims, or just doing whatever comes to mind. Recently I've been playing Vlad Straud's backstory (ft. the vampire sims from the Maxis gallery). I made him human and played out him being turned (by Elle DeVampiro, who he eventually betrayed) up to him becoming the Grand Master we know and love.