Ocean Village are fine, been on two of their cruises. No black tie evenings, lots of excursions (but these are expensive; most of them you can just walk off the ship and arrange for yourself locally at half the price), good choice of food; and flights and tips are included in the price. (Drinks aren't.) With any cruise, don't book straight from a brochure, it's always cheaper to look at the ads on the travel pages in the weekend papers or go to a cruise specialist like
http://www.1st4cruising.com/ Cheapeat and commonest ones tend to be Carribean in the winter, Med in the summer.
I love cruising, and generally age is no problem, though some of the older ships with older customers are a bit more formal; but you'll never be banned from a dining room for not wearing a ballgown.