I would think that you would want a second room but you will certainly pay money for both especially since your going in June when the parks are going through their regular season. It remains to be seen if the FTP will return and a lot may certainly depend on how the economy will be at that time next year. You can always hope that it does return and jump on it when it does (it really is a good bargain).
Other options to consider. As you are considering renting two rooms and if FTP is not brought back then I would tell you to purchase one AP for yourself or your wife and wait for the room codes for AP holders to come out. This should provide some sort of discount of at least 30-40 % off both room cost. I would consider a few other options as well as you have plenty of time to ponder. Even though you want to stay someplace different, you may want to consider going back to CSR and renting a suite (combined 2 rooms together with 2 bathrooms) and if you buy AP discounts would apply to the room. Also, for the cost of what you are going to pay for two rooms you could probably rent one of the trailer type homes in Fort Wilderness. This can be a great option as your on grounds but feel like your camping, have plenty of room, kitchen, living room and 6 people can easily sleep there. The bed room has double bed and two bunk beds for the kids. The living room had a full pull down Murphy bed for your Mother in law. The only draw back is there is only one bathroom. You may want to also consider renting points for either two studios or a two bedroom condo from someone selling their points on the DVC board. Two studios at OKW would be great if a 2 bedroom condo is to expensive. Lastly, some offsite hotels such as Holiday Inn Family Suites and Radisson Resort offer pretty good deals on their rooms (HIFS has several different type suites that your kids will love and RR makes offers for 1/2 off if you reserve a second room). These are always worth a try. Happy researching.