Hello Dandy,
I too, am very pale, and burn easily. I also tend to get sun poisoning rather easily too. And if that's not enough, I've already had to have some skin lesions removed that turned out to be "pre-cancerous." So I now use and spf of 30 or better on my face every day, even here at home in Ohio, even in the winter. And If I'm going outside, I use it on all exposed skin.
So, as you can guess, I have to use really effective sunscreen when I go to the Caribbean. My favorite one is Specta 3, which is made by Coppertone. It has an SPF of 50, and yes there is a clear difference in how well a 50 works, over a 30, or even a 45. At least on me. With the spectra 3 I almost never burn, actually I get very little additional color at all. And when I return to work after our cruises, people tend to think that I never really went on a vacation at all.
Here's one more idea . I also us Heliocare, which is UV protection in a pill form. Heliocare pills are taken daily and are active within half an hour of your first dose. Don't get this wrong, Heliocare pills are not a substitute for sunscreen ! But they do help your skin handle the sun it does get.