This is one of my favourites counties in England. There is so much to see and do if you like history.
Rye is an amazing town and I like the B&B just behind the church. Great breakfasts. Also, there is a pub called the Ypres I think and the food and beer there was always really good.
The coastal towns are good and some still have their castles such as Deal and Walmer which I think are amazing. There are also the old martello towers.
Beachy Head is famous and there is a cafe/hotel there.
I like Romney Marsh and the drive out to Dungeness and of course, the Bluebell Railway at Dymchurch.
The Long Man at Wilmington on the South Downs.
There are also a lot of parks - the Seven Sisters is a collection of chalk cliffs and are amazing...and of course, the White Cliffs of Dover although they are not so white any more.
For specific activities and events, perhaps check out http://www.eastsussex.gov.uk/leisureandtourism/ over 10 years ago
Why not hop on the train to Lewes. It's on the edge of the Downs so take your walking boots with you. And a large wallet of cash to spend in the amazing antique shops and little boutiques. A trip to Lewes wouldn't be complete without a) lunch at Bill's and b) a drink in the very cosy, Lewes Arms pub. over 10 years ago