We have been to a Cobham bus event in the past, at the MOD Chertsey site. Riding on the buses was liked, but stactic display of buses was not.
Lookout Discovery is a regular haunt, so done that to death a bit... though always somewhere to go when all else fails.
Some of our regular haunts are:
Coral Reef, Lookout Discovery, Legoland, Alice Holt Forest, Fort Nelson, Marwell Zoo, Watercress Line, Local Railway Exhibitions, local softplay (which I don't like much, as it is boring for me!) such as Jakes, Little Angels, Wizy World etc.
Hadn't thought about National Trust places... good thinking, won't risk going inside though - but certainly Polesdon Lacey has some nice walks in the grounds and surrounding area. Thinking of that, a walk in the country does well - but alas in our local area footpaths are closed at present, due to F&M disease control.
More suggestions most welcome.