How do I suggest changes to my boss in a tactful way?

My boss, who supervises my SF coworkers even though he lives in DC, is a great guy--friendly, fun, and hard-working. He's just not, well, particularly good at leadership (he is not that organized, forward-thinking, or in tune with staff development). He runs really bad conference calls--no agenda, always an hour long (even when they could be 15 minutes) and he never seems to know how to make them motivational. He has been on vacation the past week and left me in charge of running our calls. For the first time in 3 years, we had an agenda, and the calls took 15 minutes. Everyone else commented to me on how great it was to have an agenda. I really want my boss to take the hint, but I don't know how to approach him without making it awkward. How can I make him think that HE thought of the idea? How can I help train my boss to be a better manager? I have tried leading by example but it doesn't seem to get through. Any advice on "managing-up?"