Do try to reserve a Cabana at the CCR in T5 if possible. It is not very posh but you will have a private shower, land line phone to make FREE calls to anywhere in the WORLD!! You can order food to be delivered to your Cabana room too.
Decor however is VERY dated in those Cabanas.
I have only visited the JFK CCR once but if I remember correctly they may not offer dinner until after 6pm?
You can also try to enjoy some spa treatments at the Elemis spa in T5 but you need to make a reservation online as well. That is complimentary.