Sounds like you are describing OCEANIA lines. They are a new line that has had great reviews. We were on their Regatta last fall. Smallish ships (684 passengers), open seating dining, "country club casual" dress, incredible food and I could go on. Only negataive rather pricey internet connections.
They will be starting SA trips this fall with their INSIGNIA, the two ships are identical, newly renovated Renaissance ships.
This is the best I could do with their website: