a 20% discount at all WDW restaurants. I know we have the dining plan available, but I don't always go to a high end dinner nightly and just one or 2 nights of a longer stay would be great.
How about 1 or 2 DVC families a week gets a stay in the castle after the current Millions Dreams promotion ends. Picked at random, this would make it very special and also a nice perk to tell potential new members that they could have a chance to stay there.
monthly merry mixers, not just seasonal or you can theme them after holidays and schedule them at that time of year, like halloween, Easter, 4th of July, Saint Patrick's Day, etc.
This one might be interesting. A Magic Kingdom after hours, all nighter for DVC members that you can stay until the sun comes up. I know this will mess with nightly cleanup, but it would be cool the see the morning sun at MK. Also plan special events throughout the night. That would make being a member very special, because I don't ever recall this being done before.