If you're in a thrifty mode, this NO KA 'OI Carryall will fit the bill. It's a popular choice, while not very costly. In this price range, you can also consider this Sole Society Duffle Bag. It's a product you'll love which also doesn't cost the earth. You might also want to consider this Piel Duffel Bag. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you're willing to splurge, why not take a look at this Carryall - a great luxury choice. While you're at it, also have a look at this Saint Laurent Carryall. Yes, this item is expensive, but it does not mean it's not worth it. You might also be interested in this La Perla Duffle Bag. You won't regret the money spent!