Since no one's replied I thought I'd take a crack at it. These are just my very brief responses, based on my impressions from you wrote.
kryzak
Hey fellow GMATClubers!
Leadership + Extracurriculars: These are the ones *I* think I should focus on:
1. Company Leadership Development Program
This is good. Unlike the stereotypical engineer (and I mean stereotypical, no one jump down my throat), you've got demonstrated soft skills, and a compelling reason for getting an MBA. It's not very sexy (think inventing a cure for AIDS or climbing mountains) but it's useful. And if you can sound deep and full of self-knowledge, all the better.
kryzak
2. Company Intern Program
I think this one is actually better than the one above. It also shows the soft skills, shows that your superiors dig you, and has a nice us-rah-rah feel to it. Schools are gonna dig that you're a joiner and giver: you give back to your community.
kryzak
3. Advisor of student group in alma mater
Also nice on giving back and makes you sound like you're likely to do alum interviews or give money to the school post-MBA. Seems less interesting in terms of hands-on leadership and probably provides fewer opportunities for introspection.
kryzak
4. Tennis Team Captain/Founder
Nice. Works for the community-giving thing and shows your initiative. Tennis is a little ho-hum - again, it ain't rock climbing.
kryzak
5. Teaching/Volunteering:
This is much more interesting - sorta sexy. Also about giving, teaching teammates (math morons like me), community giving. Too bad it's not more recent.
kryzak
6. Homeowner's Association Board Member
Ok. Kinda boring. Not as strong in terms of leadership or community service.
kryzak
7. Other various diversity and social things I started at my company or I participate in.
Probably less interesting/less participation than the others. You've got good stuff to work with.