I have a friend who has just returned from Seychelles. He obviously had a great time there since he is already planning the next trip. He spent most of his time on La Digue. Anse Source d Argent is the most beautiful beach, according to him. He recommended a walking tour in coastline near Anse Source d Argent. What do you think?
I am not aware of the organized tours (still, there may be some) but you can try self guided tours. In fact, I recommend it since you will enjoy it infinitely. You should start at Grand Anse. The place is wonderful but not safe for swimming. After that I suggest you go to Anse Cocos (there's a nice path).