Again, another dumping ground for neat ways to work with Vim.

To change two vertically split windows to horizonally split

Ctrl-w t Ctrl-w K

Horizontally to vertically:

Ctrl-w t Ctrl-w H

If you have them split vertically C-w J to move one to the bottom

If you have them split horizontally C-w L to move one to the right

To rotate in a ‘column’ or ‘row’ of split windows, C-w C-r