Brighton Museum and Art GalleryBrighton Museum and Art Gallery is a free, council-funded local museum whose entrance is in the Pavilion Park.
Its entrance hall has a design reference collection of chairs and a nice collection of Art Nouveau furnishings, and there's a hall alongside with a large pottery collection.
Further into the museum, there's a section on the history of Brighton that includes models of the Old Steine area, and the old Chain Pier and West Pier (although it can be difficult to make out details, as the lighting in this area of the building isn't great). Further back there's some Egyptology, and upstairs there's a cafe with scrummy-looking cake, significant collections of costumiery and wall art, and a couple of large spaces that often hold temporary visiting collections and exhibitions. The way that this usually seems to work is that one of the two visiting upstairs exhibitions is normally free, and the other one is chargeable.
One of their more notable recent free exhibits was a history of colour film and colour cinematography, which featured examples from the Brighton and Hove area.
Brighton Museum is probably a great resource if you're studying art or design at Brighton University, but it's not so much of a general-purpose tourist attraction unless there's a particularly compelling exhibition event on. People with an interest in design tend to rather like the place (the building itself also has some interesting tiling work), but it's not necessarily somewhere to keep kids amused.
On the other hand, it's free, it's situated in a nice set of gardens, it has a very interesting shop, you'll probably be passing it anyway on your way to the Pavilion and Tourist Centre, and if you or your entourage decide that it's not your cup of tea, you always have the option of baling out and eating your sandwiches in the nice park outside.
Brighton Museum and Art Gallery homepage