DVC seldom offers anything for their tours. On occation, people get meal vouchers out of them - but there haven't been reports of even that lately.
The only timeshare booths in DTD will be DVC.
My two cents, having never gone.
1) How much is your time worth to you? Two tickets you'll pay $25 is only worth about $50 to your family. If both of you go, spend just the 90 minutes, plus half an hour each way in transit (2.5 hours) - that's $10 an hour for your time. We always value our vacation time fairly highly - its limited and we have a lot to do on vacation - so giving up half a day of it would have to be for more than $10 an hour. But you place value on your own time.
2) Can you deal with the sales tactics? Some people are such pushovers that they'd buy even if the salesman wasn't pushy - and timeshare salesmen tend to be pushy. You don't want to save $50 and spend $14,000.
Another good peice of advice I've heard, go in with resale info in your hand for their resort. If you would buy a timeshare, you can usually get it much cheaper via resale. However, this does show some interest, so be prepared.