I personally think welcome bags are a nice touch even if it is just family.
You could do something simple like:
1. bottled water with a personalized wrapper or a hanging tag like hotel's do with your wedding monogram or logo. Make the wrapper/tag in advance then buy the water bottles and assemble there.
2. candy bar with personalized wrapper or some other kind of food for them to snack on late at night
3. aspirin pouch with saying "because sometimes all of that magic hurts a little"
You don't have to spend a lot of money making them and on what you put in them, but I guarantee they will be appreciated and loved. An inexpensive solid colored gift bag with a diecut Mickey head for the tag with the guests name on it would work if you need to pinch pennies.
If money is no object include a small bottle of champagne or wine and plastic wine/champagne glasses.
Go check out the Dollar Tree as they have a ton of Disney things that might be fun to add to a bag/basket, especially for the rooms with kids.
Have "what are you celebrating pins" made for everyone.
Snacks...cheese & peanut butter crackers, nuts, candy, etc.
Check out this thread on the creative boards as there are lots of great ideas for things to make...there is a post somewhere on the thread for things to add to a gift basket:
http://www.disboards.com/showthread.php?t=2179996&highlight=gift+basket
The list is endlesss...