When I 1st saw the DDP rates for 2010 I was a little surprised to see the different rates for different travel dates. My in-laws had intended to use the DDP when we all head down for our big AKL adventure in January. In looking at the dates/rates the highest rate (I think that's the $47) makes sense. When my brother and I took his girls down in late May we had to pay the "holiday surcharge" at a lot of the restaurants. The dates for the higher DDP rate seems to coincide with when Disney would be charging the holiday surcharge anyway. In many cases, using he DDP during this time could still be a wash.
Also, when the free dining was extended into December the hubby and I looked at switching the trip from January to December. When playing with the numbers to see if it was a worthwhile thing to do I figured out that for my in-laws it would be less of a "discount" than it would be for us. My sons will be 12 & 13 in December. "Free Dining" would save us $160/day. My in-laws just have the two of them so it would only save them $80/day. Not so worth it for them vs. us.
We've also considered doing the dining plan again in January and paying the $168/day additional. We look at it more as a way to pre-pay the dining. For the 8-nights we have booked it would add another $1344 to the trip. We generally "budget" an even $2K. Even with the DDP I'd expect to be out money on drinks and snacks. Plus, you have to pay the gratuity now. We did the DDP once before and it felt like we were running from ADR to ADR trying to get our quarter's worth. It wasn't much fun at all. It's not the value it was back when we did it before, when each person got an appetizer, entre, dessert, and non-alcoholic beverage. I'm not so sure the DDP is the way to go for us. We have so many options for discounts, tho: FL Resident, Passholder, Disney Visa Cardholder, etc. It's not hard for us to find a good rate wherever we may be staying.
Aaand, I bought my TiW card back in May so it will still be good for January. With the 18% forced gratuity I see the discount I get with my card as just covering the tip. I will say this: I will not tell my servers up-front that I'm TiW even though I know I'm supposed to. I know a server at LTT and we talked about this at great length. He says he doesn't blame me one bit. So many of the servers see the TiW guests as a gimme and don't really try to give them good service since they know they're already getting at least the 18%. This was how we have felt in the past and it was confirmed by my friend because he's heard other servers talk about it. I want the option of leaving the tip that's earned. At one of our visits to Chef Mickey's last January we had horrible service. Instead of using our TiW card we paid the full rate for the meal and left the server like $1+change (so we didn't have to wait another hour for him to come back with our change). It didn't cost us that much more to just pay the non-discounted amount and leave what little we did. It certainly felt better to do it this way. On the flip-side, if we get good service we use the card then leave another 10%-15%. It's the least we can do when the server has made our trip that much more enjoyable.
I think with discounts and the DDP it's up to each person to spend the time to figure out what's available, what works for them, and what's worthwhile for their own trip.