I have spent many hundreds of dollars on the allegedly finest wallets. The smaller ones are always too small to fit everything, and the big ones are always too big to carry around with you. Nothing beats the simple rubber band.

Coins just go in any old pocket (I never put those in a wallet anyway). Paper money gets its own rubber band and goes next to the credit cards. I put the credit cards in my front pocket and then put the paper money on top (away from my leg) so the cash doesn't get damp in case of sweat.

I also carry a larger zipper case full of my other essentials (passport, drivers licenses, checkbooks, foreign currencies, stacks of hotel/airline/travel cards and IDs that I might need). That goes in my briefcase. At the start of each trip I decide which cards I need for that trip and put them in my rubber band wallet. Everything else goes back in the briefcase. The zipper case I use is a Rimowa Lufthansa first class amenity kit like this.

I could probably leave the zipper case at home but sometimes my plans change mid-trip and I want a different set of cards.