The Zoe top handle pouch is surprisingly roomy. Most of the other top handle pouches look silly on me (i'm 5'7) and don't fit comfortably under the shoulder, but the Zoe actually looks great on. I'd highly suggest a mini skinny. I have a wonderful Marc Jacobs large wallet, but I rarely use it because it just adds extra weight and bulk to my bag. I'm able to fit everything I need in my mini skinny and just keep the extra stuff in my wallet at home. If I'm going on a big shopping trip or something and need all my gift cards and what have you, It's there and ready to go, but honestly, I have no need to lug around all of my cards on a daily basis.
If you want a little extra room and are willing to spend a little more $ I'd suggest a mini wallet. I know I'll be buying the madison mini wallet as soon as it hits the store and I also love the old bleeker version (maybe you can find one on ebay or an outlet). There are also some older mini wallets floating around on ebay.
btw, I agree it's a shame they didn't come out with mini skinnys to match the Zoe collection. I'd love a patent red or black mini skinny. Also, the aubergine is really tough to match! The only things that really work with it are gold or white/cream.