You do not want to take too much luggage, but you also do not want a bored toddler on your conscience. Select the toys you want to take for the journey, and wrap them. Choose some old favourites, along with some new surprises, so that you can re-find the favourites on the journey, becoming a heroine in the process. Unwrapping adds a few precious minutes to the entertainment potential of each item, and greatly enhances their perceived value. Reconcile this with the fact that younger children will probably play with the wrap, and this plan is sure to be a winner.
Older kids are less easily distracted, though wrapping still helps.
Take a tin or plastic box and put in it all sorts of things for crafty creations felt pens, scissors, PVA glue, sticky tape, wool, fabric, paper, ice block sticks, old greeting cards, beads, buttons, feathers, stickers and of course some used gift wrap. Cut a piece of sticky backed plastic to fit the inside of your lid and stick it in. Use one of those slightly sticky feeling dishcloths to make a cover for the lid and base of your tin, and keep an off-cut for those wiping out games. This will help prevent the tin sliding off the airplane tray and into a messy heap in the aisle. Try to limit the glue applications, but otherwise, let imaginations run wild.