If you're staying in a hotel at Disney or in the resort area, check with the ticket booth person in your hotel. I recently had lunch at the Gaylord Palms Hotel and noticed they had an actual Disney ticket sales office there and inside they advertised some kind of discounted 1-day ticket good only after (I think) 3pm or 4pm. You had to prove you were there for business or a convention.
I think the concept was that a lot of people are in Orlando for meetings and don't want to pay for a whole day ticket when they can only use it late afternoon or evening. (And in some cases the park(s) are not even open very late off-season). So check with your hotel or call Disney and ask them if this is sold at other locations.
BobK/Orlando