In building a grid of text I find myself wanting to free-flow text into a frame of infinite depth and fixed width with an option that allows me to return the height that the frame would require to display the text, in twips.
As I track row heights, this would allow me to know which rows would fit onto a page and which I would have to roll over onto following pages.
So in my wishlist I am looking for a .ParaTextHeight function.
Look in the Tips and Tricks section. A while ago I posted the basis for a paratextheight function (in Visual Basic) that I use. It probably needs a little modification, but you can start there to get what you want. You can then get the height before you actually print it.