I created simple diagram with several nodes and tried to layout it automaticaly. FlowcharLayout works fine, but resizing nodes to fit text is urgly. None option KeepWidth, KeepHeight works as expected: nodes becomes too narrow. The best results obtained with FitSize.KeepRatio but calling it twice also split words.
What is the best way to automatically resize ShapeNodes to keep complete words inside? 
I assigned text via Text property.

Thank you. Actually it was my fault: paddings were incorrect and took all height.

ResizeToFitText returns false with KeepHeight if it can't fit the text at all in the current node's height. E.g. if the Text is "line1" + Environment.NewLine + "line2", and the node's height is as big as the font size, it won't be possible to fit both lines without increasing the node's height.

If you need to fit the text as tightly as possible and don't care about maintaining some aspect ratio, you could start with a very large size and call ResizeToFitText twice - once with KeepWidth and next time with KeepHeight.

I hope that helps,
Stoyan