Shirley Cress Dudley responds:  I admit I had some help on this one.   I asked my 16 and 18 year old what kinds of things they do, when they are visiting their Dad, and their 3 year old half-brother.  Here's what we came up with:

• Watching kid's shows are fun.  (My teenage kids can sing the songs from Bob the Builder and other TV shows.)
• Going to a drive-in movie together (G rated or animated.)  Get out the blankets and the snacks and make it a fun evening.  If the little ones fall asleep early, you can even watch a double feature (maybe PG?) after the younger ones fall asleep.
• Family night- order a pizza, rent a movie and watch it together.
• Holiday Activities- decorate the Christmas tree together, dye Easter eggs, carve pumpkins (little ones use markers to decorate pumpkins)

And basically, do anything you can, together, as a family-

• Prepare the meal (little ones set the table or put out napkins)
• Clean up after dinner (little ones carry silver wear back to the sink
• Wash the car
• Clean the house (little ones can "dust" and carry little loads of laundry to the laundry room

Good luck to you, in blending your various ages of children.  Just treat them fairly, love them all, and they will follow your example and be good siblings to each other.

For more information, Read 52 Fun Things to Do under $25.