There are a couple of good baseball related restaurants in the area.
Don & Charlies
in Scottsdale is a must - it is where all the players and club personnel eat, and is a unique experience, the walls are completely covered in baseball memorabilia and autographs. Last year, I saw Michael Taylor of the A's when I was eating there, and overheard some interesting stories from the long time clubhouse manager of the Giants, who was sitting at the next table. Willie Mays was apparently there a few nights before. You might want to get a reservation though, since there can be quite a long wait for seating otherwise.
Also, there is a TGI Fridays literally inside Chase Field open all year - you can request a table in the outfield stands, and even if you don't eat there, they let visitors walk around the balcony area, if you have any interest in seeing the inside of the Diamondbacks stadium.