I can vouch for the Lowepro line... I have the Lowepro runner and while containing the dslr in the main room opened from the front, the back has a side pocket with ziplock that can contain a mbp or an iPad with no problems.
Also the Runner comes with a build in raincoat, so you can have it with you in all weather.
They also come in various sizes, so no need to get scared by the amount of space in this one 😉