Daman and Diu is best for those who wish to have a relaxing holiday with a coastal paradise, anyone who visits this place is guaranteed to have a blissful vacation while enjoying the sea breeze, resting on the beach chair and enjoying the waves of the sea. It is generally a weekend getaway destination. Further, there is a huge influence of Portuguese culture in Daman and Diu. This is one of the main reasons why tourists flock to the region a lot. It is also due to this influence that you can find a lot of stunning architecture, lip-smacking food as well as breath-taking art and crafts in Daman and Diu.
Depends on own preference.
If visit for beaches then definately Goa / Gokarna etc. are best.
Daman beaches are not that great but are good place to visit. Among both Daman & Diu, Diu is preferred.