The tuiles should be kept in an airtight tin, but unfortunately not for very long as they will go soft.
For the ideal tuile about which I spoke before, it is also a matter of taste, I am the only one at home to prefer them well cooked (no "white" in the middle), well browned and very crisp.
To serve an ice cream or a sorbet with a tuile stuck in the top is a very very good idea.