I have only been to Wisley once, and that was a while ago. If my memory serves me, it is a large area to walk around. I remember seeing some vegetables in trial beds. There was a show on at the time, so there were large leeks, etc.. But that is about all I can remember.
Ryton is not as big as Wisley (methinks), and is easier to walk around. There are compost displays, an "allotment", a bee garden, the all muck and magic garden, fruit trees, herbs gardens. There is a childrens garden with a playhouse. There is the "Vegetable Kingdom" which includes displays, a view of the seed saving area (for Heritage seed library) and a chance to look at some of the more bizarre varieties of veg/fruit. The shop is well stocked with foods, drinks (including cannabis lager), as well as gardening supplies (seeds from the organic gardening catalogue) suitable for organic gardening, bird boxes, "houses" for lacewings. bees. ladybirds... etc. The restaurant has a nice menu, and there is a cafe. Think entry fee is less than a £5 (free for members of RHS? and of course, HDRA). Had a good day there on Tuesday.