With a 9 month old AND 2 other kids I'm going to assume that space,laundry facilities, easy transport, resort facilities and finance are all factors.
If space and having access to a kitchen, laundry facilities (both of which the cabins provide ) transportation and resort facilities (both of which are debatable)are main priorities but money is less of one have you considered either taking a one bedroom DVC unit from Disney or the cheaper option of renting points from a DVC member?
The cheapest of the DVC, points wise is Old Key West, which offers a huge one bedroom unit with master suite ( kingsize bed and jacuzzi) a separate living/dining room and fully equiped kitchen area. The Living room has TV/VCR and two couches one is a queen size pull out sofa ( for the 2 older kids).
If you want the space AND the luxury of resort quality accommodation and facilities the DVC resorts offer you that, but they are more expensive. If you can avoid Friday and Saturday nights where the (points) cost of the rooms more than doubles you should be able to rent points from a member that would give you a per night cost from about $200 a night ( as opposed to about $400+ direct from Disney). Do remember though that this is a private deal between you and the DVC member, Disney nor this site take any responsibility for any transactions so it is advisable to take some precautions if you decide to go ahead with this method of getting accommodations.
Here's a link for the DVC board where people put up their points for rent
http://disboards.com/forumdisplay.php?f=29 , here's a link to the point calculator
http://www.wdwinfo.com/resort/dvcpoint.cfm . Just put in the dates you're thinking of travelling, the resort and the unit size ( a studio is the same size as a hotel room, one bedroom is as I decribed above) , you will then get a points cost per individual night and a total for the trip. It will be immediately obvious how much more weekends cost, so if you can avoid using weekends you will quickly see how much difference that can make.