Stop worrying Alsbaby, cala D'Or is fantastic for a family holiday.
If my memory serves me right the C D playa Apts are in the Cala Gran area which is very central. 5 - 10 mins walk to the centre and perhaps 20 - 30 mins walk to the Marina but with loads of bars/restaurants in between.
You'll find you can wear anything in the evening and not feel out of place and children will be welcome in all the restaurants.
Don't worry about finding places to eat before you go, there's so many that you're bound to find loads you like the look of!
Although the Marina is more expensive, it is good to go and see how the other half live!!
I'm sure you'll have a great time - it's fab!!