The times my Sims have had vacations / "Adventures" have been fun, but like you SaltyPaws, I'm always very "nervous" before I go on vacations.
World Adventures has always been pretty buggy (at least for me), I was hoping Ambitions would patch it, but I don't see trips to France (the one that seems buggiest for me) improved much (if at all); in fact, my "Excavate" action's been broke since Ambition shipped.
Let's hope Car Stuff has a robust patch in it to fix vacation problems, but there's no telling.
I just ensure I save the game before any vacation, and as soon as my Sims arrive at their destination, I save another version of the game (with a different name). Then, if my Sim gets stuck or trapped on vacation, I can at least "roll back" to the point before they left.
While on vacation, I save repeatedly, the only time my game's crashed is when my Sims are on vacation, so I go into "save, save, save" mode.
I've never had any corrupt saves, so this has worked for me when I've an opportunity I don't want to miss (or want to go grab some of the vacation specials like the martial arts toy or the Nectar Maker).
And I did have success (twice) with a "work-around" when my Sims were stuck on vacation: I'd become close friends with a "native," and invite them to "Move in." Once, the game looked like it froze for a minute or two, and then the load screen popped up loading the "normal" town. The other time, it just acted like the vacation was over and loaded up the "normal" town.
Both times my Sim was returned home, without the person my Sim had invited to move in. So it "sorta-semi" worked getting my Sim back home, but it's not worked consistently, and I still can't figure out why the Sim from vacation venue didn't "return back." Most likely the game was already seriously messed up, so there's not telling what was going on behind the scenes.
-- Happytime