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

Why not be straight up? I look my Boss straight in the eye and tell him what I think, "From my experience". Granted I was placed into his office by strategic persons looking out for his best interest, but he also understands my interest is in making MY workplace the best ever. He doesn't always agree with me but he listens and we've made some great changes! I think the secret is to not be arrogant and acknowledge he/she is the Boss and ultimate decision maker.

tell him what you did and how it worked.....he may try it....most of all be honest

In addition to whatever else you decide, it certainly wouldn't hurt to have your coworkers share their comments with him -- not just to compliment you (although that's a plus too), but they could casually mention how great it was to have an agenda, or anything else ('Oh, how was your vacation? Oh yeah, we did fine while you were away. By the way, did you hear about Orly's great agendas? It was a neat way to do the calls'.... for example). As long as they said it in a not-insulting and not-planned-seeming way, it would help no matter what else you do.

Also, perhaps suggest to your boss some medium of feedback -- for all of you. Maybe five minutes at the end of the calls, a form (anonymous, monthly, whatever), etc. A mechanism for fresh ideas, comments/suggestions, things people really like, etc to get to him, or to get flowing around the office in general (whichever seems more appropriate to the culture). By creating a structure for the kind of feedback you want to give, you can then give it more easily -- and it's removed enough if you put it in a for-everyone, positive light.

by the way, not to say 'scheme' - i agree with the comments above to be strait and direct, just adding these other ideas depending on what might fit the environment

If your boss is the receptive type, perhaps you can come up with the agenda for his first meeting back from the vacation, and email it to him before the meeting without really making a big deal about it.

You can use him just coming back from vacation as an excuse. Something along the lines of: "Since you just got back from vacation, I took the liberty of listing a few discussion items for your consideration. I think if we cover these items in our next conference call, we'll have safely covered the things that really need your immediate attention."

If he uses your agenda and runs a really tight conference call as a result, then everyone else can send him compliments off-line about how well he ran the conference call. Hopefully, the good feedback will motivate him to come to the next conference call prepared with an agenda of his own.

This approach offers the following benefits:

(1) He'll be more likely to feel that having an agenda for the next meeting was his own idea; and

(2)If he's really a good boss, he'll still realize that it was your initial input and initiative that gave him the 'idea' in the first place.

IMHO, having other people compliment your handling of the call in his absence has the potential of back-firing -- he may resent you (consciously or unconsciously) for making him look bad by comparison.

Hope that helps in some way.

I agree: be honest! But I don't agree that you or any of your workers should "innocently" let him in on your great agendas, etc. Unless the guy is a total blockhead, he'll resent your back-handed self back-slapping.

You’ve identified many areas in which he needs improvement.
Some are huge (leadership, motivation????)
You certainly can’t bombard him with all at the same time, so going one at a time is probably best. You can also see how he does on that.

Maybe the best way is simply to help him. Give him the notes from the meeting you ran AND a draft agenda that includes the issues that need to carry over to the next one. Simply make some appropriate categories. Offer to review all at the time and elicit suggestions and make reccomendations for the next agenda. Get it typed and sent out.

Repeat for the next one. Either he will pick it up himself or just let you keep on doing it, unless he is so far gone that he simply doesn’t care. If that seems to work (ie he either hands it all over to you or takes it on as his responsibility) go to the next one.

I’d go to motivation.

Make it a question like “What would happen if we used Open office instead of Microsoft office?” If that doesn’t work then try subtlety peer pressure him into improving.