Re: Can I have multiple households vacation at the same rental lot?

@leftwithbreadYou can invite anyone on vacation with you. You can also edit the vacation lots via Manage Worlds to accommodate max 8 Sims allowed comfortably.
Some lots are big but basic. If the other Sims are not in your household you can't control them and say, put them all to bed so night times go slowly as they never seem to sleep. But you can all holiday together as long as you invite them. You can also invite them once you arrive. In fact, if you have a keyholder they usually keep joining you randomly anyway. Which is a bit bizarre if you're in a tent in the middle of nowhere and they appear and randomly grill burgers non stop. When you want to send vacation buddies home you just interact with them and select Send Home... nobody takes offence!
You can also visit other holiday makers just like you visit other Sims homes.

Edit: I've always just done this while booking the vacation, say using the PC. I just select who I want to take a vacation with just like travelling on a night out.