Here are 2 tote bags made from the same pattern (free online from South Sea Imports or Wilmington Press). The one on the right is floppy and folding over on itself. The one on the left has firm foam batting which keeps it standing upright. As I get older and have a harder time bending down to the floor to reach the floppy one, I really appreciate the people who have brought firm foam batting from the car industry to the quilting world.
We carry 'inn-control plus' which has fusible web on both sides. Remember to put parchment paper between the batt and the ironing board if ironing on one side only. I used the foam in Brenda's pattern, 'My Monster Bag'. The bag is large enough to carry 2 queen size quilts so it is wonderful that the bag doesn't flop over when empty.
Brenda uses this batting in many of her bag patterns. 'The Elipse Bag' above has the batting in the main body of the purse. When open, the bag stays out of your way as you search inside.
Either type is easy to sew through and makes a wonderful addition to your bag batting choices.