I did a bit of work many years ago going from solidworks to 3DS Max to the unreal engine. Back then I found that optimising poly counts was best done in 3DS Max. That said, if you export as STL from SolidWorks, you can tweek the export resolution to begin with. However if you push it to far you'll end up with some poor results, 3DS Max will let you optomise the polygons far better. The exact export settings from SolidWorks I found to be dependant on the complexity of the model.
In short, don't spend too much time on the SolidWorks export and concentrate your efforts in 3DS Max, it's tools are far more advanced for that type of work.
However, if your models have a lot of internal detail you don't require, you may wish to run the defeature command first, create a simplified model, then export that.
You could have a look at the trial of Moi3d. While I have not used it myself, I'm aware that many people are using it to get good meshes from nurbs.
Moi3d won't take a SolidWorks file directly, so you would need to use STP. Its developed by the same person that originally coded Rhino way back ... According to comments on the Moi forum, its mesher is better than Rhino's.