Gordale scramble can be a bit intimidating if wet (a bit polished and slippery in places). I certainly wouldn’t do it downwards, so wouldn’t include it at all in the loop above. There’s a load of nice, easy paths down from the tarn which don’t include Gordale.
Personally at that age I’d be trying to tempt them up Pen y Ghent or Ingleborough using the promise of cakes and ice creams. Pen y Ghent is the shorter walk of the two. The best route to Ingleborough is the one from Clapham that goes past Ingleborough Cave (well worth a visit, ice creams available), Trow Gill, Gaping Gill etc.
If you’re looking for stuff further afield, Wharfedale has some nice things. Burnsall has nice bit of river for paddling and swimming, Bolton Abbey has the Strid Walk and nice eats, or the walk up to Simon’s Seat for something a little more challenging.
Skipton Castle is OK, not worth a special trip though.