Look for something that is lightweight but durable. Depending on price range flylite or Samsonite are good options.

I would go for a suitcase with wheels!

If you go for a suitcase make sure it is on 360 degree wheels. This makes it a lot easier to move around.

Oh gosh whatever else you do make sure you get the ones with x4 wheels instead of x2! It was so much easier to travel with children with that kind as they wheel more easily.

Thanks JILLIAN! Good advice and wow! all 4 for $110! That is impressive!

look at your local markets I just bought ones that are carry on size and hard case that are lightweight and have 360 degree wheels which were handy considering I have 3 kids (2,9,11) and we bought 4 cases and one of them had to wheel 2 cases at once.
My 2 yo was able to manoeuvre it!
Because I bought 4 they were cheaper I got 4 for $110