I've been using k-epsilon much in the past, but today I'm thinking about working with k-omega. I understand omega is a function of epsilon (i.e. omega is the specific dissipation rate), and the models may have some advantages over the k-epsilon models. Can anyone add some insight as to how, where, and/or why the k-omega could be more beneficial, and can anyone tell me when how to choose from the standard and from the SST?

I have ever used standard k-w and sst k-w in mixing layer simulation. I found that standard k-w was not good. The sst k-w was more agree with the experiment data than standard k-w.

yes, you're right. SST kw performs better because the freestream air does has much influence in the eddies motion. But a standard k-w does.