Originally Posted by Aviatrix
Of the places/language you mention I'd go for Spanish first, then French or Italian, Dutch last. The Dutch expect to use English with foreign visitors, and I have only ever once come across an adult Dutch person who didn't speak English - a bus driver many years ago. In Spanish-speaking countries, on the other hand, you will come across people who don't speak English, and you will need to know some Spanish for everyday transactions such as buying things in local shops.
I agree with Aviatrix: I'd study Spanish first. Not only are there many Spanish-speakers who don't speak English, but it is also generally considered to be easier than French, Italian and Dutch -- the pronunciation and phonetics are easier than French, and the grammar (at a basic level, at least) is as easy or easier than the others. Also, once you know some Spanish, then Italian and French are much easier to learn. (The reverse is true too, of course.) And many Dutch people speak amazingly good English.
There are a number of places in Latin America that specialize in teaching intensive Spanish to foreigners. I did some courses in Antigua, Guatemala that were very good and a real bargain -- and it's a beautiful and fascinating country too. I'vce also heard of courses in Mexico, Costa Rica and Ecuador, and I'm sure there are more - do a web search. You might try a combination vacation / 1-2 week course to get you started, before then heading on to visit other places.
Good luck,
Michael