I just finished 5 tote bags and I used light/medium weight fusible interfacing on the lining and all the pockets. Works great.

When I made the inside pockets I use fusible interfacing (medium weight) and divide the pocket as stated above. If I want a full width pocket I make it a zippered pocket.

That was my thought for a bigger pocket, a zipper.

I use some iron-on interfacing when making the pockets to give them body -- I also make them smaller to fit the use.

I took a purse class several years ago and the instructor told us to put our cell phone in the pocket and then pin it. Sew that and then add a pocket for tissues and then for a ballpoint pen. Lipstick pockets whatever. I try and customize mine in a general way because everyone has different items. I do not have floppy pockets at all.

i use elastic in the top

What about just using craft backing? It's rather stiff.

I like iron-on fleece inside the pocket piece. Then, of course, separate the whole wide pocket into sections to suit you.

OOOhh, I like the idea of elastic!

Very pretty bag. Looks like you've got a lot of suggestions for the pockets.