I myself have north of 300 but I think you should volunteer because you like it and it brings you joy, not for college applications.
Local hospitals always look good
Check out:
https://www.volunteermatch.org
http://www.idealist.org
http://www.createthegood.org
And many similar.
I volunteer when I can for Pets for Vets, when they need helpers for fund-raising events. Always great to spend time with fellow vets and be around animals.
If you volunteer for an obscure non-profit, check them out on Charity Navigator or GuideStar to ensure they are legit.
Some other favorites of mine:
USO
Team Red White and Blue
https://www.teamrwb.org
Department of Veterans Affairs
http://www.volunteer.va.gov
All states have their own department of veterans affairs or state veterans department or agency. There is often a state veterans home which welcomes volunteers to visit with vet residents with no families, assist with computer work or to read to them. Here's an example for Maryland:
http://www.charhall.org/content/volunteering/
There are hundreds of opportunities out there.
You can see I focus on vet-related work. Listen to Flieger/ALO Steve, though, when he advises some variety.
Hi!
(((putting on my ALO hat...)))
I like to see potential candidates showing me a variety of community service hours: hospital, food places, places of worship, youth groups, etc. The variety shows various interests and a desire to help others; not just a specific group.
How much do I want to see? I don't have a number and I know USAFA doesn't either. "Enough" is a great answer but extremely vague: what is "enough?" I would say if you're taking a full academic load, and occasionally have an after school job...during job season or sport seasons, volunteering is tough; everyone knows that. When you have the time...IF YOU DESIRE TO DO IT, then go forward with it!!
I've had candidates with hundreds of hours of service, and some with 30-50 total. What mattered was why and what else they did.
Steve
USAFA ALO
USAFA '83
Quality -not quantity - of volunteer/community service is most important.
As with most of the application process, have a RATIONAL/LOGICAL reason on WHY you chose to do something. If you chose to visit 100 different sites/organizations to do community service...why? If you chose 5...why? Your BGO and MOC interviews are likely to ask questions using this reasoning (i.e. why choose one SA over another? why would you turn/not turn someone in for an honor offense?). There isn't necessarily a right or wrong answer to everything!