Well, as a 33 year old father of two, I understand, but...
I've finally figured out how to run a good game without spending a lot of time in preparation. The trick comes from being able to select the right modules and being able to tie them together. I'm using a pre-packaged campaign setting (The Wilderlands), pre-packaged gods (The FR pantheon, with minor changes), two main modules (Tomb of Abysthor and Rod of Seven Parts (2e)), and a few other minor supplements (Artificer's Handbook for magic item creation, WoTC splat books as needed by the players), and really not much else.
I spend approximately ZERO hours each week preparing for the game. If I have spare time at work, I might tinker with the treasure in a given room to make it more unique or interesting, or stat out some beasties to fight, should the players choose to fight them, or work up a few plot hooks and ways to tie in player backgrounds, etc. Those things don't take much time.
I run monsters as they are from the book - I don't spend an hour statting out a bad-guy for him to die in 5 minutes. I don't spend two days drawing up a map that the party will ignore, or bypass, or run through in 4 hours. It's not worth it. It's all about ROI - return on investment.
For me, it makes the most sense to use pre-packaged stuff, tweak it ever so slightly, and just adlib the rest. The game is about killing stuff, and advancing the story. For me, pace is everything. My players love it, and they're clamboring to play week after week.