JenniD44 - I understand your dilemma, it's hard to consider another kind of vacation when you have been so happy with the tried and true.
I have a few thoughts, don't know how helpful they will be.
Your savings is partly due to booking a cheaper room category; did you have the 30% room discount on your prior booking? That saves nearly $200/night on the SL CL room cost in the first week of December, if available. The first week of December does not include the higher T'giving rate, so that would be a savings all by itself.
I know Disney is making it harder for families to consider vacationing without a dining plan (crazy high OOP prices), but have you looked at pricing your meals w/o DP? For DD and I, we end up money ahead or at least dead even when we pay OOP over the DP, I've run so many spreadsheets!
We rarely eat dessert, so that is a waste for us on
DDP, even without CL - with it, we eat our dessert in the lounge. We usually get one appetizer and one entree and split, the portions are so huge. We rarely have anything but water to drink in the restaurants - we need the hydration, and any soda/tea cravings are satisfied in the lounge.
I know you have 3 kids to feed, but do they really eat $59/each per day? (is that the going rate now? I don't even know!) With the CL food, we would waste food at the restaurants, we stopped booking so many table service and now only have 1 per day. Big breakfast in the lounge, lunch on the go or in a TS restaurant (cheaper costs at lunch time, bonus!) and split a QS meal or just eat in the lounge for dinner.
Do you have an AP? The 20% TiW discount helps off-set dining costs. Might be worth looking into getting one adult AP for those discounts, if you don't already have one.
You could play around with your dates, see if anything comes up with CL and free dining. (or, do they specifically exclude CL?) You could check each day to see if someone cancels and snag their CL booking. We are often able to get CL rooms last minute, or as the vacation approaches, people cancel all the time.
If none of this appeals to you, and you prefer to keep your current reservations, don't worry. You will still love the GF!
We alternate between garden view and CL (btw, I would drop the lagoon and just go with garden if it's available - lagoon view isn't nearly as charming, IMO, and costs far too much extra) and always have a great time.
As to your question for more space - you could request a corner room, many of them are larger. No guarantee you would get one. Or, try to book the deluxe garden view rooms, more money but they have the extra sitting room area. You would have to ask for a rollaway, though, no daybed.
Good luck!
It's a tough decision.