Very senior people are best used sparingly. Put too many of them on a real project and pit them against each other (as the old MSFT performance review process tended to do), and they start beating their chest and trying to backstab the other people they're competing with. OTOH if you put them in research and tell them how super important their project is and how it's advancing the state of the art and stuff, and you might get a few years of reprieve.