Please recommend restaurants in Santorini.Also tours that are worthwhile.

Aris restaurant next to the Loucas Hotel in Fira is where we had our best meal with fantastic views. Rick Steves recommends it as well.

All my top picks are in Oia. We like Skala (very large terrace overlooking caldera, lovely open-air ambiance in evening) and 1800 (extremely pricey but lovely food housed in an old sea captains house - GORGEOUS). Also, Katina's tavern at the harbour in Ammoudi. This is a great place for post-swim lunch!

http://www.selene.gr/
This is a really nice restaurant in Thira with a great view.

When I was in Santorini last month, I ate at 1800 (in Oia), Selene and Koukoumavlos (in Fira). The best food was (by far) 1800. Koukoumavlos has more inventive cuisine but inferior service (at least the night we were there). All three are wildly expensive. For a more modest alternative, I really like Taverna Nikolas in Fira as well as the gyro shop on that same street.

There's a great ouzeria in Oia called ... Ouzeria. It's run by two guys and the mezze there is fantastic and really excellent value. It's slightly off the main drag - look out for a sign beside the public toilets on the main pedestrian street. You pass a lovely Indian restaurant (Karma?) on the way there. We ate there last week, and looking out on the rain now, I wish I was back there ...