If there is a destination that has holiday weather all-year round, you should always travel off-season. You will enjoy the same place, in the same conditions but for a much lower price, at a much easier pace and the crowds will not be there to wake the agoraphobic in you.
Another good reason is that you can drop in unannounced at the Lonely Planet’s « our pick » hostel and still find a bed. This is what we did today and it was as easy as arriving home. We are now in Puerto Escondido in the state of Oaxaca, México. A beautiful place. It is still a bit crowded with local tourists despite this not being the season because local tourists come here any weekend if the weather’s good but you can still get around without feeling like it’s too crowded.