It depends on what goal you are trying to achieve. I went from a 50" to a 60" plasma, trying to have a better, larger, viewing experience. After a few days with the new set I wanting to upgrade the size. I would say that if you have a chance stop by a local store, walk off your approximate seating distance and see what you think with the different screen sizes. I went to a local shop and sat infront of a 90" Sharp and at first thought it was huge untill I went into another room in the store and sat infront of a 110" projection screen showing the same movie. My next upgrade will be a projector and screen unless "they" make a reasonably priced 110" flat panel. Also, Im no expert but a 15' seating distance should put you in the 120" , or slightly larger, screen range.