I am getting really good results with SW Pro Classic waterbase using Floetrol. I am not really having to be too careful, either. I see brush strokes but they lay down as it dries.

Sounds like you are using the right techniques. Are you painting over perfectly smooth trim, or does the original surface have brush marks from a previous paint job? If you're painting over brush strokes, no matter how smooth the new paint lies, the brush strokes will show through somewhat. A thorough sanding will help smooth down previous brush strokes.

Are you allowing a good 24 hours for the paint to dry before evaluating? It takes that long in some conditions for some paint to lay down.

Assuming you're painting over an acceptably smooth surface, then it may be the paint you are using.

I, like jockewing, have good results with the ProClassic and I don't use Floetrol with it.

I find it's hard to get a perfectly smooth surface when you're painting on vertical surfaces. It's best to take a door, e.g., and lay it horizontally, if possible. But with trim, you don't have a choice. You just have to do the best you can. Often, when I'm working very closely on something, I obsess over every imperfection, but when I stand back a few feet from it, it looks fine.

Good luck.