The Marina is a great choice! Nice room, classy athmosphere. For the beach, you can choose between Karon that is closer, or Kata, further. Direction Karon, you have on the right hand side, on the road not the beach, smaller local restaurants, next to each other. Had good food in the third last, heading Karon.
You have the advantage, to be in the center, with all the restaurants and shops.
For a first timer, motorbikes can be dangerous and tuk-tuk are expensive. So your location is a great advantage.
I booked the boomerang cottages. I drive a bike, so for me this is fine. A bit far to walk to the beach, and a climb back to the place. Could be interesting for those, who don't mind. It is not far from Kata center, but you have to cross busy Patrak road! Very good price quality.
Phuket Resort - Boomerang Village Cottages