Oh wow, I thought I was the only person who seriously worried about this sort of thing. So bad was the frizz factor last year in Orlando that I actually avoided the camera. Dumb move, as now I have a bunch of photos of my son at WDW, but none of me. In previous years I have given over to clips, hats and headbands.
I live in Sydney and we have some pretty fierce summertime humidity.
When I was younger my hair was curly but as I've gotten older the natural curl has sort of "fallen" and now if I dry my hair naturally, even with oils and specialist conditioners, it just goes into a dull, pouffy, frizzy mess.
I have to agree with the poster who recommended the Keratin treatment that you get at the hair salon.

It made my hair soft, smooth and frizz free but it still has body and bounce, and most of all - shine! It survived a Sydney summer beautifully, I only had to blow dry on a few occasions when I was in a hurry and couldn't wait around for it to dry naturally, and even then I could just blast away with the drier for 10 minutes or so and it fell into place - no need to section clip and brush and smooth and section clip and brush and smooth etc etc for half an hour, only to have it all puff up as soon as you leave the air conditioning.
It's pretty expensive down here, but after your wallet gets over the shock

you end up saving a lot in expensive conditioners and salon blow dry's, and the freedom it gives you is great. I now actually don't dread summer like I used to because of what it would do to my hair. And if you get it done at the beginning of summer it last the whole season through.
I'm looking forward to testing it out in FL in a couple of months - am having the treatment done again a couple of weeks before I go. Also looking forward to seeing how it handles in the rain and fog next year in London.