Which way do I go?

I've been in a funk the last couple months because, to put it bluntly, I don't know what to do with my life.  My children keep growing up, becoming more independent, more amazing, which is just what I intended, but I have worked myself right out of a job. They just don't need me anymore.  Well, they need me, but not in the same time-intensive way that they did when they were little.

Which means I have a lot more time on my hands.

And I don't know what to do with it.

Oh, I have options.  I could get a job, a paying one, as a nurse, probably.  Or I could go back to school, and get my masters degree, something that is on my bucket list. Or I could do more genealogy work, or more volunteer work, or keep working at the cello....really, the possibilities are endless.  And I am so blessed to have so many opportunities.  Except that I don't know what to do with them.

Here are the things I do know:

1. My kids are my priority.  I want to be there when they leave for school in the morning and when they get home after school and I want to go to all of their games, performances, etc.
2. I want to do something that is new and challenging. 
3. I want to be busy, not insanely so, but enough that when I get to the end of the day, I can look at it and say I accomplished something.

Okay, I thought that list would be longer.  See why I'm having a hard time deciding?  

I took this to my husband, who gives great advice, and he suggested I try volunteering with some organizations/companies that I think I might have an interest in.  He also suggested taking a few classes at the colleges here to sort of sample different pursuits.  

It feels like I'm in high school again, trying to figure out what I want to be when I grow up.

Any ideas?