It looks like the NORMAL average temp for the time period you are vacationing is in the high 60's to low 70's. If you plan on using a pool that can be heated, I'd probably go for the HEAT. However, if there is a heat wave and the temps hit the high 70's low 80's more than likely the heat won't be needed.
It's a hard call with the weather these days. Nothing seems to be "normal" at least around here in NJ
. Can you request the heat and if it's not needed (you'd have to watch the weather closely) cancel it out before you get there?