Got back two days ago from a fortnight in the Animal Kingdom Lodge, and stayed a the Grand Floridian a couple of years ago. I know it's probably a bit late for any advice but will give my thoughts anyway?!?
We considered staying in a cheaper Disney hotel but went for AKL as it included the dining plan (didn't have that last time and spent a fortune on food as we had no car so were v restricted to eating on site). The better hotel including dining was about the same as one of the cheaper hotels and paying for food. Dining plan was ace, DDs are v fussy so it took the pressure off paying for food that they might not like (obvs we did pay for the food but the dining plan is pretty good value and since we had paid up front for it I didn't stress about it on hols). Staying on site means you can get to the parks early, although the days with Extra Magic Hours tend to be busier than other days so not always worth it. DH had some app (I can find out what it was) which predicted crowd levels at each park (inc Universal and Kennedy Space Centre) which helped us plan our days (crowd levels vary hugely day to day).
We hired a car this time which was LOADS better than not - it was included in the package (from Virgin) - you had to pay a bit more for their insurance but we saved money on transport to Kennedy and Universal so it pretty much cancelled out. Also lovely to be able to drive to a supermarket for extra fruit and cereal (dining plan doesn't give you every single meal so some days we just had cereal in our room before heading out). I really hate public transport (boring IBS type issues where I feel the need to be in control of getting to a loo, nice!!) but managed fine on the Disney buses. Having said that we drove to Blizzard Beach as it's dead easy to park there, and Hollywood Studios when we saw Fanstasmic as the queues for buses after the fireworks can be long.
Kennedy is brilliant, we drove it in a little over an hour. Make sure you don't accidentally drive through the tolls without paying, we're expecting a fine to follow us home from the journey from airport to hotel where we didn't really work the system out
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Universal is completely fab, the Harry Potter ride is my fave ride of all the parks and since your child is bigger they'll probably adore it (DDs are a bit smaller and not so great on rides so Universal has slightly less to offer us). You get utterly soaked on their water rides so make sure you go on a warm day!
My biggest tip (esp if the crowds are likely to be big), is register with them asap and book your rides using the FastPass+ system. From 90 days before you go you can book up to 3 rides a day, you get an hour slot to do each ride without having to queue. You can also make dining reservations this early and if you particularly want to do any character meals it's probably worth considering. For instance, the Seven Dwarves Mine Train ride is new, and when we were there queues were maybe 70 mins and you couldn't get a FastPass as they had already all been allocated. I'm not queueing that long for anything(!) so we just didn't do it. Can't say I'm bothered but I think DH is a bit gutted not to have had a go.
Sorry I went on a bit there. Will have a think about anything else and let you know...