This is a real issue for the hilton properties in Paris: we faced the same situation (2 kids) this summer. In the end I booked a cash stay at an IHG property (Voco Montparnasse) because they had a family suite that wasn't that much more than a standard room...for the Hiltons, the suites that could accommodate 4 were more than double the price of standard rooms (so two rooms on points/ cash would have been cheaper).

tb