WHen i'm on vacation, I try and stay very active. Also, many hotels have at least some sort of gym/exercise equipment that u can do alittle on. And there are many gyms u can just pay for the day. Granted I don't lift as much as I normally would when i'm on vacation, but still try and lift some. Plus any hiking, swimming, etc.
If i'm taking time off cuz i'm COMPLETELY worn out, I usually just do some form of cardio.
A few yrs back i took 3 full weeks off over Xmas break(i had been really overtrained and didn't even realize it, just got to a point where all my lifts started going down and down) came back after the break and i was up over 20lbs on bench. No bs. All my other lifts went back up 2.
So sometimes a break is good. Just depends if u're really overtrained or if u're just telling yourself that cuz u don't feel like working out.