Weddingbee boards

I don't know about jewelry, but I have some ideas for activities.  For the sake of everyone around them, all activities should be non-noisemaking! If it makes noise, make sure earphones are included!  Movies tend to work well, though if they are too young or have particularly short attention spans, this may not be an option.  Coloring books and crayons are typically good.  I have some really great books with magnetic pieces that you can move and place in different places; Colorforms are good too, as kids seem to like the interactive part and they can move all the pieces around to make their own pictures.  I would probably avoid playdough (at least for the 2 year old), as it may be difficult to keep it off their clothes and the seats.  Little action figures/toys (age appropriate with pieces of course) are always good, and books are nice too. Travel-size games and puzzles are pretty easy to find now too and may work well for the 5 year old.   

I would probably just try to avoid anything messy or something with a lot of pieces (unless they are something like the magnets or colorform pieces that stick to their holders). Try looking at Target or Micheals in the dollar bins for cheap items.  I love those bins; they have such great deals!

Just a fun tip: I have individually wrapped items before to pull out at different times on long trips.  This way the child gets to "open" presents, which tends to be a big hit, and I can prolong the excitement.  (For example, wrap the coloring book/crayons, toy, book, and a puzzle/game separately and give the child something "new" to open every so often. The longer the trip, the more "presents" you'll want, or you can increase the amount of time in between their openings.)  

I don't have any really good recommendations but I wanted to second the idea of wrapping each gift individually.  My mother bought my nephew school supplies(!) and wrapped them each and put them in his new backpack.  You would've thought it was Christmas Day.