The new mini is super for travelling, I've done it myself (also in combination with an iPad). It's the ideal combo, the iPad's super battery life is great on a train or plane, and the mini is the lightest possible Mac available (even beating the 11" Air if you include its power supply, and far more powerful than one). It's great if you have a keyboard, mouse and monitor at your destination.
You know the mini has an integrated PSU now right? Well to be more precise the 2010/2011 models do, or do you still have an older one?
I usually put my mini in a soft sleeve meant for a 10" netbook, the one I have is a perfect fit although it's a bit too long (as the netbooks are more rectangular), I get around this by tucking the loose end into the opening.
I then bring it in a standard APC laptop backpack, I put the iPad in the padded laptop compartment and the mini in the back compartment which is smaller and fits snugly. I point the tucked-in part down so it has more padding in case I put the backpack down on a hard surface (it also helps that I have 2 SSDs in my mini so no moving parts except the fan).
So yeah good luck and maybe report back what you ended up doing, I might get some ideas from it 🙂