Let me see if I can help out the OP a little....
You bet most cost effective option for what you would like to do it 2 rooms at a value resort. This will give you a total a 4 beds and 2 bathrooms and the most important feature...a wall between each room.
You will also have 2 other options in this same price range. The first would be PORS. They have rooms that will sleep 5 and the cost will be slightly less the 2 rooms at a value. The only problem is you will only have one bathroom and the room it not much bigger than a single room a value resort.
The next of the two low cost options in one of the value suites. These are actually 2 value rooms that have been modified into a suite but they are actually much nicer than 2 rooms at a value resort. They are laid out to have a master bed room, a small kitchen, 2 bath rooms and a living room that converts into a bed room. These are great when you have 3 to 4 kids and 2 adults but loose a bit of their luster when sleeping 2 set of adults. Also they have very limited availability and are very rarely offered at a discount. In the grand scheme of thing that can cost nearly as much a 3 discounted standard rooms at the same resort.
In your particular situation I would look at either 2 rooms at a value or depending on your budget and time of travel stepping up to two rooms at a moderate.
These are not your only options though. There are a myriad of options at the DVC resorts, deluxe resorts, and camp grounds but all will carry a heartier price tag.
Feel free to drop me a line and I will be more than happy to give you a call and go over every scenario that will fit your needs as well as get you pricing on everything that interests you. Hope to hear from you soon.