Whitlenge Gardens, near Droitwich/Kidderminster.
Bodenham arboretum
Webbs - the Wychbold one has a big garden centre and lovely riverside gardens, the Hagley on has a Falconry centre which isn't expensive at all.
Little Owl Farm Park off the A449 just past Ombersley is really lovely.
There is also Whitley Court and Gardens, Hanbury Hall, Harvington Hall.
And if all else fails, a sunny walk down the canals are lovely, especially around Salwarpe, Wolverley and Hanbury.
There's a mini golf place in Wolverley.
Stourport is pretty with a riverside play area, arcades and Shipley's fun fair.
Wyre Forest Visitor Centre - Gruffalo and Stick Man trails, play area and cafe with loads of forest walks, only have to pay for parking. There's a Go Ape there too at separate cost.