I live near Bognor - I'm not from here (mercifully). It's a bit of a dump, but these things spring to mind - the Town council hold the Clown Festival once a year, there's also the Bognor Birdman rally. Other than that, you've had it. Unless you'd like to watch chavs cavorting in the rain for a few days......
As for themes - single parenthood, no employment, Tesco, tourist trap, kiss-me-quick holidays, Butlins and MacDonalds.
Best head off to Arundel (nice big castle, wildlife and wetlands trust, river walks), Chichester (Festival Theatre, Jazz festival, nice Georgian buildings), Littlehampton (Sea centre, funfair, newly developed river area and marina), Singleton (Weald and Downland Open Air Museum -old buildings, farm stuff). West Dean (lovely old house and fantastic walled garden), the South Downs (sheep, grass and more sheep). You'll have much more fun.........
Where in Bognor are you actually going to be?