We love Rosa Rossa. It is a great choice for Venice. Your kids will like it too after you tell them itis Johnny Depp' s favorite place. His jacket is there in a glass case in one of the back rooms. The food is good, the prices moderate, and the atmosphere pleasant and friendly.
I am more sure what "seating charge" David is referring to, but it is not a scam as he claims in the Tourist Scam section. Many restaurants all over Italy charge a coperto or cover charge of 2€ euros or so per person. It is stated on the menu, generally at the bottom. And bars and cafes charge different prices for beverages, depending whether you sit at a table or take them standing at the bar.
The cafes on Piazza San Marco charge high prices for beverages if you are seated at a table while their orchestra is playing. You are paying for the pleasure of enjoying the music while seated. (Just as you would pay to attend a concert). But many of us just walk by and enjoy the music for free, and go have a beverage somewhere less expensive.