I use the smallest Wenger laptop backpack I've seen. Wenger is the Swiss Army Knife company and they make GREAT products. I found my current bag at Sam's Club for 19.95 and it has a laptop compartment which I put my MBA into with a sleeve.
You would need a sleeve for the iPad unless you have an Otterbox or similar style case on it like I do, but there is room for it easily.
Plus a smaller pouch for power cables, etc. I also enjoy that all their bags have a Media Pocket with a hole coming out for headphones.
It's not for everyone, but it's a very easy and efficient solution for my needs, and super compact and light (more than you would think when I say backpack).
EDIT: If you are interested, I could snap a shot of the main laptop compartment with my MBA 13" and iPad in there if it would help you. But if you aren't interested in a backpack style I won't waste my time