Where to spend 1 day in Surat Thani?

We're travelling from Khao Sok to Surat Thani town where we're catching the night train to Bangkok, so have a day to kill somewhere in that area.

Any recommendations for spots to visit? We will need to leave luggage somewhere (prob Surat Thani station - so could catch a short train from there). We've got a small child with us, but otherwise flexible.

Any decent beaches (esp if less popular with jellyfish), interesting attractions or fruit farms?