have you seen this article on vacation happiness?
the only point I'd add from personal experience is the level of happiness long after a vacation when you look back at pictures of a perfect trip. I can feel the boost. I use it on days when my nearly-there flower garden is is being covered in wet fluffy plops of snow. and the weather says it will be continuing for the next 3 days.
so instead of going outside I enjoy the bright reflected light all that white crap sends my way and look at old vacation photos. and plan all the trips we have coming up. and be happy.
my plan is to just always have a vacation no more than 8 weeks away.