I wear my Apple Watch all day and charge from 8pm-9pm(roughly) and then wear it to bed using Sleep Pulse 2 to track my sleep and movement and heart rate. Love that... I also use the silent alarm to wake me every morning and my wife really likes that feature since I get up before she does. I then use the watch as my workout tracker with the workout app and my fitness builder app running native. When I shower, I sometimes wear it in the shower if I am all sweaty or else I give the watch a little bump charge while I shower and get ready. Usually it is enough time to get it back to 100%. Overnight, it usually goes from 100 to 92-94% and it burns about 10-12% during my 1 hour workout.
All in all, I typically wear the watch 20-22 hours a day. If I hit all my goals by 6pm or so, I take it off for a break, but I love the features and look, so I wear it a lot and the silent alarm and sleep tracking is well worth it.