I don't know if I follow you exactly but usually content of two different sources (as in different expansions or stuff from the Store) don't influence each other. So having a casino on a resort lot will not add to the value of a resort.
They will probably use them on the lot but I doubt you'll get their gamblings as income.
This might not be true though and I haven't really used the casino myself so my suggestion is to ask in the Store forum over at thesims3.com.
The people there know their store content in and out.
Thanks, I'll do as you suggested and ask my question at 'thesims3.com'...
