Also better to look forward rather than out the side, and much better in the front seat than in the back seat (less yawing motion). For many kids, that means a booster of some sort to elevate them above the panel.
Getting back to the electronic bracelets--Mah Woman is especially prone to both air sickness and sea sickness. When we've chartered boats, she always wears her bracelet. On one trip, we were in especially rough water, with waves crashing over the bow onto the cabin. I noticed that she was turning the bracelet up (it has several levels of juice), asked her how she was doing, and she said, "Great--this is really fun!" That one example made the expense worthwhile.
Cary