Your children are at the upper end that most of the attractions in the Jardin d'Acclimatation are aimed at but I still think that you'd find it a very pleasant half-day out:
http://www.jardindacclimatation.fr/
(The English language part of that site seems to be still awaiting construction but you can still learn a great deal, irrespective of your knowledge of French, by clicking on the tricolor).
The Jardin d'Acclimatation is an extremely attractive park which even adults without children enjoy visiting. However, there are plenty of rides, animals, shows, etc which are mainly for youngsters (although adults enjoy them as well). There are also several places to eat, ranging from cheap caf�s to very upmarket restaurants. It's about a million times more civilised than Disneyland. There's a small admission charge for entry. (�2.70 per person). The rides and attractions are fairly cheap, especially if you buy the carnet tickets. The nearest Metro station to the Jardin d'Acclimatation is Les Sablon, which is on Line 1 or you could catch the little train from Porte Maillot (Metro Line 1 and RER Line C).
Another park well worth visiting is Parc Andr� Citro�n. (Nearest stations: Balard at the end of Metro LIne 8, Javel Andr� Citro�n on Metro Line 10 and Javel on RER LIne C). It's principal family attraction is the tethered helium balloon in which you can ascend to get some great views over Paris:
http://paris.15.evous.fr/IMG/jpg/Parc_Andre-Ci troen.jpg
However, if the sun's shining, your daughters should take their swimming costumes. The fountains, at one end of the park, provide a wonderful playground for youngsters:
http://b5.imgsrc.ru/