Both would be correct (but don't forget the tilde on trópico).
irme adds a slightly different nuance, something like "I want to leave for the tropics", only the Spanish sentence occurs more frequently than its English counterpart.
For example, the following sentence doesn't sound as common to me: "quiero irme al cine". Here, quiero ir al cine is more natural.
In the "irme al trópico" example, there's more emphasis on leaving where you are, whereas in the "ir al cine" one, the emphasis is only on where you go.