I work out very regularly while not on vacation, including when I travel for work. I work out about six days a week and my work outs are split between weights and cardio.
Most of our vacations involve overseas travel and we do a lot of farm stays and non hotel types of stays at places that do not have gyms. However, many of these vacations are active and involving hiking, sight seeing and being out and about and moving anyway, so I generally do not feel too guilty. And while I may not run, we do take long early morning walks too when possible since we are early risers anyway.
At least for me, I am fairly disciplined the rest of the time, so a break from the formal workout routine every once in awhile is probably good. I am at the point when I probably need a recovery week soon even without a vacation.