2 x Crockfords rooms sounds good, but if you think it's a little bit steep, can try exploring 2 x FWH Superior Deluxe instead.
The mentioned crockfords rooms are around 520 sq meter, while the Superior Deluxe at FWH is only 320 sq meter. Price wise, I think the FWH Superior Deluxe should probably slash your bill to half.
I have no idea what type of Genting Grand suite can accommodate your entire entourage in one room. Even if it could, it will probably work out to be more expensive than 2 x Crockfords hotel rooms.
Even 2 GG rooms may work out to be similar, if not more, than the recommended 2 x Crockfords hotel rooms. Also, Genting Grand is about15 over minutes walk to Skyavenue, unless you are expected to spend most of your time at the Genting Grand Complex - Vision City Video Game Park (which is very unlikely).
As for FWH WCR, one room is definitely not enough to squeeze 3 adults, one kid and one baby, unless you wanna make your elder, or wifey, sleeps on the sofa. I think you will probably still need 2 FWH WCRs, which may not be readily available, even during "low" season.
It's always a big headache bringing our loved ones for vacation. However, fond memories are priceless, which money cannot buy. When in doubt, and if you can afford... Just pay, and enjoy! Cheers.
PS: Alternatively, (if you are still stuck) just walk in to any WTS or 707inc outlet and see whether you can grab a package from them. Good Luck!