1.  Stay on property if financially possible.  It's much easier to go back to the hotel and nap in the afternoon if it's close by.

 2.  Bring lots of water and snacks.  You'll spend a fortune going to restaraunts and snack shops every time the kids get hungry.

3.  If you're in the middle of potty training, bring plenty of extra clothes, and don't get so excited yourself that you forget to stop for bathroom breaks every hour.

4.  Stay flexible!  Don't make too many set plans, as your children may have different ideas.

5.  For some downtime, go see Playhouse Disney.  My son fell asleep in the middle of it.

6.  Character meals are always a hit.  They are usually a little pricey, but SO much fun.  At WDW, I recommend Chef Mickey's and the Playhouse Disney lunch (I can't remember the name of the restaurant.  It's at MGM and features JoJo, Goliath, and the Einsteins).

7.  Souveniers:  Allow the kids to look during your stay, but tell them that you aren't going to buy anything until the end.  This gives them the opportunity to look to see what they want, without you having to buy at every store.  If you do buy in the middle of the trip and are staying on property, the stores can deliver the items to your room.

I know that there is a whole lot more, but that's all I can come up with right now.  Anyone have anything to add?