We have a 10ft Challenge. Originally came with a 6ft awning. Replaced it with a 8ft awning. I reckon trying to maximise your covered space is the goal - over things like stainless steel kitchens etc.
Go the 14ft - sounds like you've already made the decision.
Friends of ours have huge All-Terrain. They've never had issues with size of sites in caravan parks.
We have bunks for 2 boys (9 and 6). They work really well for consolidation of space. Other friends have 2 sets of bunks for 3 kids. One of the levels is a space for holding the clothes boxes.
Welcome to the wonderful world of camping!!
Challenge C/T - Offroad, Softfloor camper
Tool box, Water Tank, Gas Bottle, Kitchen on tailgate, 10Ft Tent