Here's how we handled tipping at WDW:
Mousekeeping--we did not tip them since we don't ever tip in hotels (nobody does around here--I had never even heard of it until on the disboards).
If you normally tip at a hotel, I would go ahead and tip at WDW--but if you normally don't tip, dont feel like you are obligated to at WDW.
Magical Express--we did not tip the driver when he dropped us off, since he didn't handle our bags. I didn't see anyone else tipping him either. However we did tip him when he dropped us off at the airport at the end of our trip since he loaded our suitcases. We tipped him $5 for two suitcases.
Magical Express luggage delivery--We didn't tip them since we weren't in the room when our suitcases came (we were at Epcot). If we had been in the room, I probably would've tipped $5 just because I would've felt funny not tipping when were were standing right there.
Wait staff--we were on the dining plan, and only tipped extra once: we had an excellent server at Liberty Town Tavern. I would only tip "extra" if it was wonderful service.
Kelly