As a mom to two very young kids my first reaction to your title was "she's so lucky!! I wish I had a few hours of alone time!!" I'd get a pedicure and see a movie and then I'd go for a drive and play music really loud so that I could barely hear myself singing along and I'd get my hair done and if it was a Saturday I might go see if there are any open houses in my favorite neighborhood by the beach because I love seeing the inside of staged homes and I'd pick up a few scoops of gelato and try to people watch (but not really people watch because it feels totally creepy so I'd probably end up in my cell phone doing something much less interesting than watching random people walk by), etc.
You do not need a man to make a few kid free hours feel fun or indulgent.
If you'd like more suggestions of random solo activities, check out Groupon or Living Social. I know there about a zillion yoga classes, art lessons, cooking class, etc. that you can do on the cheap through those sites. Enjoy your Saturday to yourself. I'll be living vicariously through you when you report back on the fabulous adventure you had, all by yourself.