Vismayah food is OK. But I used to take a beer sat on the corner with KK Road and watch the world whizz by, (good street food there).
CK describes Koh Lanta as quirky - it's fantastic. You drive back up KK - U-turn under the flyovers at the end - then it's easy to get back to Vismayah from there.
Make Koh Lanta the first night of your Hols - you'll love it. Massive 'open air' restaurant with music and swans but there is a large music/night club there to enjoy too.