First, I loved the trip report and how you brought in the side trips back home. We just went to our local botanical gardens in STL, and the Cherry Blossoms were beautiful. It makes me want to visit DC, which I have never done.
Second, I have the same dilemma. I have a conference the first week of November, at the Contemporary ($219/night), and was worried if I would get enough out of it. I have convinced myself I will, and DW will be able to join me on the end of the conference for a few days without the kids. Can't pass on that price and we will be able to attend the food and wine festival, which is a very fun time at EPCOT. Hotel costs and some food will be reimbursed as well.
Third, MNSSHP is a lot of fun. We have done it with the kids. I think it is much better than the Christmas one, as it really changes the look and feel of the park. It always feels like Christmas when you visit WDW. You may want to check on the rainout policy, as I don't know how the refunds work.
Fourth, I read all of your posts, but may have missed, so I apologize. What was the weather like there in January? We are going in Jan 2014 as well with DD (9) and DS (6). I like the earlier hours, but didn't know if it would feel like you were getting everything out of the parks from a time perspective.