I've been with DS and tbh I wasn't impressed.
There are very few "big" rides (and they are pretty tame but that's ok given the child demographic they are aiming for).
The issue fundamentally is that the whole park is over subscribed, so the wait times can be enormous for all the rides, whilst they can be unfeasible for the the big ones. Even with a Q Bot we queued 1.5 hours for the Ninjago ride only to find it was closed for a technical issue at we got to the front of the queue
(we never got the chance to go back given wait times for everything else - again with QBots).
A day should be ample to do the park properly but without the fast track Q Bots you don't have a hope in hell in getting through even half the good rides and with them you're still not guaranteed to cover everything.
We stayed in the on-site hotel (simply not possible due to location to do in a day) and whilst the rooms were nice the restaurants were poor. I'd say that's true overall for the park.
I know you're a captive audience so am not "green" about prices but compared to Alton Towers for example the food prices were as high but the quality terrible (whereas I've had some really nice food at AT - pricy but nice).
So definitely bring a packed lunch if you can.
The most relaxing bit is the model village. If you can find a spot it's a good place to picnic.
The Star Wars exhibition is good if you're a fan, but if not I'd give it a miss.
If the weather is good the splash park is great fun for the kids (remember to pack a change of clothes, suncream, bag for wet clothes/swim gear and lightweight towel) but be prepared to need ear defenders as an adult and be somewhat stressed out as keeping track of your children when it's busy is an exercise in cosmic patience/futility/angst. It's definitely worth having an agreed meeting spot if you lose each other.
Sorry to sound so negative. Tbh I'd never go there again, BUT DS loved it and I guess that was the point
.