You should be able to leave everything hooked up without issue, if you have no leaks.
I literally just found 3 kegs on gas after 2 years. (Yea, I'm a terrible homebrewer)
The 5# tank was left on. The whole time. It's still full!
If you're concerned about leaks I have 3 bits of advice. Number one is a spray bottle of StarSan as mentioned above. If you're really paranoid, unhook the serving lines. That immediately eliminates the out QD's and the faucets for possible leaks. Also, Keg Lube is your friend. A little bit goes a long way, and it seals great. If you have an iffy keg lid or a QD that doesn't like to go on or off well, it does the trick.
The only way you lose a keg of beer on the floor is the output side leaking somewhere, and that's very rare (And almost always caused by a picnic tap getting wedged on)
Most of the time if you find a leak, it's because the Co2 tank is empty.