Good Dining in Marina Del Rey
Hal's Bar and Grill on Abbot Kinney (not strictly MDR, but close enough) serves 4 salads for dinner - www.halsbarandgrill.com
Manuel's salad and the artichoke-tomato salads were both certainly large enough to be split among two for a starter. The other two salads might also be good - but I haven't tried them. The meat and fish entrees are expensive here, but hey if you wanna stick to salads or veggie plates, this won't break the bank.