D.,
My second is almost 21 months, and still nurses, primarily before naptime and bedtime, she'll usually wake once in the night, then sometimes in the mornings when I want to lay in bed a bit longer, and "soak" (we co-sleep).
For my oldest, we were in the same routine, and she self-weaned a month or two before her 2nd birthday. I had heard about the vacation-thing, and sure enough, it worked for us. We happened to be at Disney World, so we'd get up in the morning and go-go-go then doze off on the way back to the hotel for a nap, then after nap get up and go-go-go until it was time to go back and go to bed (of course, dozing off on the way back, again). She kind of forgot about it, so I assumed that as soon as we got back home and got back into routine, she'd ask again. She didn't for a couple of weeks after we got home, and when she did, I told her, "I'm sorry, Baby. Mommy's boobs don't make milk anymore. Would you like some Ovaltine?" Sure enough, she went for it. :-D
We don't really have a vacation planned in the next few months, so I'm not sure how we'll handle #2. I'm traditionally NOT a fan of the just deal with it/cry it out method. <shrug>
Best wishes and luck to you!
M.