Great that you are asking this question early!
All other things being equal, leadership, particularly in the community, is where I'd love to see you work the most. Marathon-running is good up to a point, but top business schools are looking for impact: how do you, as a leader, impact OTHERS? Leading groups of people training could be one way; but how about having an interest in a cause that's truly outside yourself, that benefits the community you live in?

The top MBA programs are looking for a history of genuine commitment rather than, say, a one-off volunteering role or one-to-one tutoring once a week for six months in advance of your application. If you've got a year and a half before application, this would be a great place to maximize your investment.

Additional coursework is good, but if your GMAT is 730 (I realize that's a target) they already know you're smart, so additional coursework could be more like frosting on the cake; get that GMAT out of the way early, and invest as much as possible in your leadership development.

In the workplace, continue and expand your team leadership, focus on those brand-name collaborations, and if possible, get sent overseas to manage off-site teams in person. That way you'll have some international stories to add to your application. Should you chance jobs again? I don't think so -- put down more roots and have even more impact where you are -- 3 jobs in 3.5 years doesn't look as good as 2 companies and a promotion or two over the same period of time, and the promotion will give you more opportunity to build internationalism and impact.

Hope this helps!
Margaret Strother