Panniers have not worked out too well for me when it comes to lugging the laptop around. There are also those panniers that look like posh briefcase bags and they have not worked out too well either. It just doesn't work on the weight distribution.
The bag that did work best was the Carradice Camper Long Flap that I bought for my retro roadster. I wanted the 1950's look with cotton material, leather straps and buckles:
I bought an extra bracket to put it on my commuter bike and it works much more brilliantly than I imagined it would. Side pockets have luxury ready eats in them - I can access them when riding along - and tools/spare tube. The mini-pump goes in the main compartment, otherwise I am not having to open that en-route, which is good if it rains.
The 'cotton duck' material expands in the wet to become magically waterproof. it actually works well and doesn't get abraded like other bags do.
As for the notebook, it is optimally placed for weight, suspended in the saddlebag and therefore shock absorbed without being excessively packaged (it has a neoprene sleeve). Naturally there is room for my change of clothes, and, due to the 'long-flap' I can get a couple of bags of shopping in there too - Tardis like or what.
There is also a feeling of security with the notebook where it is. Off bike I don't bother with a shoulder strap, the handle does fine.
I honestly believe people in the fifties were onto something with the saddlebag. There is no need for a pannier rack and the weight distribution is so much better. Naysayers will say you need the weight low, actually you need it next to your own centre of gravity - tucked behind your bum.
Lights strap onto the bag very nicely - one less bit of stuff to not have to take off.
Perhaps the best bit of the Carradice bag is that you get admiring looks from 'CTC' vintage cyclists as well as the ladies that are into their handbags.
As for camping - I can fit tent, sleeping bag, thermarest and picnic map and some clothes.
There is an optional tool-roll that fits on the top, I have one but don't use it.