Rio City Cafe is on the water in Old Sac and has a New American menu. You could also go to the Delta King (a boat permanently docked in Old Sac) and they have good food (everytime I go, I decide I should go more often) and they also have an actual playhouse downstairs with edgy plays evenings. The Grand Dame in Old Sac is The Firehouse restaurant which is quite nice and has prices to match.

If you want to drive about a mile from Old Sac down J Street, there's a block between 27th and 28th streets that has several excellent choices, my favorite being Centro with serious upscale Mexican dishes and a great ambiance at 28th & J.