One of the main reasons I like Micro 4/3 is for compactness. That especially comes into play in travel.
tconelly on mu-43.com has converted from a Canon DSLR kit to an Olympus OM-D and large selection of lenses, including the Panasonic Lumix 20mm f1.7.
(Click Here) to read the post on mu-43.com, where tconelly describes the difference in size and weight of what he was able to carry on trips with Canon vs. Olympus.
On his Madrid trip, he shot a lot of images, and provides links to them. I would suggest at least going to his condensed set of the whole trip.
(Click Here) to see that photo set on pbase.
It's hard to imagine that he would have been more pleased with the results if he'd carried a larger camera.
Now I want to go to Madrid, as well. :)