I have the same problem with my dd, who suddenly seems to have outgrown so many family days out that we have enjoyed up to now. The discussion comes at a good time, as we made up a list together of the things she does still enjoy last weekend, I thought they might prove helpful to others:
Cooking proper dinners themselves with you* and cakes etc, playing rounders as a family/with or without friends, picnics, anything connected to canoes, boating etc, water skiing, tennis, museums (check first with them before organising anything as some won't cut it) all theme parks except for the ones aimed at very young children, safari parks, skate boarding, climbing wall, mini golf, golf, kite flying (my children love this), long walks, nature walks, day out at the seaside whatever the season, visiting new towns and cities, Sleepovers, BBQs, swimming in lakes and streams, cinema, theatre, sushi night, train rides to far flung destinations, horse riding, crafts, making cards, gifts and such like, making dens (my children still like to do this if we are in woodland etc, camping even in the garden, flea/antique markets with pocket money, art galleries are completely free, board games afternoon/evening, make a camp fire in the garden with marshmallows*
This were our ideas, I am sure once on a roll your kiddies will come up with tons of ideas. We have printed ours now and highlighted what we can do in sunshine and rain and it is on the fridge. Now (I hope) we will never be bored again... All activities with ** are free.
Link below might be of interest:
www.wildswimming.co.uk/