I prefer to micro-manage the shit out of my spare time, otherwise I find myself just zoning out in the evenings. First I figure out what spare time is available each day, and exactly the amount of time is required for tasks . . . then devise a strict routine to follow. After a month or so, I make minor tweaks as needed.
If I have four hours in an evening it might go something like this:
15 min - Walk dog
5 min - Reheat pre-prepared supper/cut veggies for family meal
30 min - Eat supper with family
10 min - help with dishes/clear table/keep son busy
5 min - Warm-up (skipping, burpees, or jumping jacks)
15 min - Squats (about 7 min increasing weights, 3 one min work sets with two min breaks)
15 min - Military press (about 7 min increasing weights, 3 one min work sets with two min breaks)
15 min - Deadlift (about 7 min increasing weights, 3 one min work sets with two min breaks)
5 min - Pull-ups (two sets of 15, 2 min break between)
5 min - stretching
15 min - Give son a bath (brush my teeth)
10 min - Dress son in pajamas, brush his teeth
20 min - Read stories to son
10 min - Deal with various methods son uses to delay bed time (pretending to need to go to the bathroom, crying because something isn't quite right in the room, complaining about temperature, etc.)
5 min - lay out clothes to be worn for next day, pack lunch for work for next day
5 min - scale/arpeggio review and warmup
5 min - soloing practice (chord tone targeting) over jazz track
5 min - improvisation over same jazz track
15 min - learning a new riff/song
5 min - sing notes, then play the melody on guitar
5 min - play melody on guitar, then sing notes
5 min - practice sight reading
15 min - read/relax before bed
The weird thing is, I don't feel like I've got energy when I get home, but once I actually start in following the routine I get energized by the things I'm doing. Weekends tend to be less structured, but I make a task list of things to accomplish on Saturday and Sunday by the end of each Friday.