In June, on which island would I have a better chance of less rain and CALM water?

About the same in both places.

calmest water and less chance of rain than any other island has to be Aruba.
friends of ours tell us GC generally has calmer & warmer water than T&C.

I know Aruba would be my guaranteed calm water but we just got back from there and we want to take the kids somewhere with good snorkeling. I did consider it though! It amazes me how Plam Beach stays calm all the time even with all that wind!

I've said this many times, but the summer hurricane season is decidedly NOT the rainy season. So your chance for daytime rain in the Caribbean in the summer (particularly June and July) is pretty much the same no matter where you go. There are some times when you'll get more rain over the larger islands (Puerto Rico, Jamaica, Cuba, and occasionally Martinique or St. Lucia) because these are large enough to actually have weather. But unless you run into a tropical front or hurricane, you probably won't be rained out of a vacation anywhere in the Caribbean. Rain showers tend to be afternoon or nighttime events and don't last long.

Am I correct that summer months tend to have calmer water?

Doug
isn't it true though that Aruba's annual rainfall is much lower than any caribbean island, I forget the exact number, but the avg amount of rainfall is really low compared to the other islands in the region. this is one factor why Palm beach is so crowded in the summer months.

that's correct about Aruba's rainfall Patsfan. but I think the main reason they have so many summer visitors is because it's outside the hurricane belt.

Yes, I'd have to agree there. The same thing would apply to Curacao which is a more interesting island culturally than Aruba. But the further south you go, the less chance for hurricanes. Barbados also has fewer hurricane direct hits because it's 100 miles further east than the other islands.