I think an interesting exercise for making the culture of middle America more salient is actually to look at the mechanics of the Sims. The devs of the Sims add things to it all the time, often in attempts to make it inclusive, but it's still indelibly American and middle-class.
You age up your Sim by blowing out the candles on a birthday cake. You make money by having a job (freelancing was added in an expansion pack), and you make more money by getting promoted. The icon for traveling to a different lot--even one in your home neighborhood--is a car. You live in a house (apartments were added in an expansion pack). The first food your Sim can make, even with no cooking skill, is mac and cheese.
Simlish isn't a language, but the language it is not is English.