As for what can only be put in a vacation hood - the secret lots, for sure. The game needs the destination type (Far East, mountains, island) for the correct NPC to spawn. A lot of actions are destination dependent, too - you can't go on tours, and I don't think you can learn the massages. Plus, you won't get the vacation memories.
Most of the other mementos can be gained "at home" - trink tea, play mahyong, eat local food etc., because the objects needed for that are available in the main hood, too. The tents should work in all hoods.
You can set up a hotel in your main neigborhood or a suburb. You can visit it like any commercial lot, but you can also check into a room and stay for as long as you like.
Are the sims charged correctly for the stay? That would be a nice opportunity to burn some cash without having to go on vacation.