It would be misleading to define it as a "vacation". In some cases, due to religious holiday observances, some restrictions on slaves were relaxed [1], however I'd say that the overall harsh life of a slave and the few instances where they were allowed to do something other than work cannot be compared even with that of a lowly modern worker. I would also imagine that any easing of work patterns would have been entirely at their owners' discretion. And of course it was impossible to resign.
[1] http://penelope.uchicago.edu/~grout/encyclopaedia_romana/calendar/saturnalia.html
Follow up: did the slaves really get three days off a week post Spartacus? I read this here on reddit here and it just sounds too much.
Vacation time would indicate benefits. This would then indicate that roman slaves had some sort of rights or that they could be expected to be treated a certain way by their masters. Roman Law and the examples of slavery from ancient sources do not indicate any such expectations.
There were strict laws on what to do with a runaway slave or how a crime committed by a slave should be judged differently to a free person. There were many different types of slaves as well. Personal slaves, domestic slaves could expect an easier life than slaves working in agriculture on vast estates or slaves working in mines. Some slaves were branded, chained, some were dressed in fine clothes.
Slaves were freed, but there is nothing to support Cicero's claim that a foreign slave, captured in war could expect to be freed after six years of service. Cicero's own slaves were not freed this early.
Slaves were property. Property doesn't get a 'vacation.'
My main source: Title: Roman Slavery and Roman Law Author(s): Keith R. Bradley Source: Historical Reflections / Réflexions Historiques, Vol. 15, No. 3, HISTORICAL REFLECTIONS REFLEXIONS HISTORIQUES (Fall 1988), pp. 477-495 Stable URL: http://www.jstor.org/stable/23232665
Arrrg my textbook is not with me but I'll fish it out when I can.
In my Ancient Rome class (graduate level course) I was taught that Romans had a holiday for everything all the time. And a god for just about everything too. I mean there was someone you could pray to about your front door. Anyways, they had all these holidays. I'm talking like once every month or so. In the warm seasons, it would be more like once every ten days. You get that day "off" to celebrate! It's a huge party with games and plays and wine and food etc. Huge party. The whole town's invited. I remember my prof saying that on Emperors (not all, but especially Julius Caesar) birthdays, the government even gave people bonuses. Like real cash.
David Potter, Ancient Rome: A New History; James Rives and Robert Graves, eds., Suetonius: The Twelve Caesars; James Rives and Harold Mattingly, eds., Tacitus: Agricola and Germania.
These were the required readings but since I don't have them with me I can't quote. I hope this helps get you started in the right direction. Sorry for so little detail, it was a while ago.
E: As stated below, I forgot the OP was about slaves and my post is in regards to citizens. My bad!
I'm not familiar with the agricultural cycle in the Mediterranean, but wouldn't there be certain times of the year when there simply wasn't a lot of work to be done?
Would slave owners take their slaves with them on vacation?