I think that, in this instance, they're too big. Of course, the first thing I would do is to blur them a bit to see if they can fit in better and if that didn't work too well then I'd just shrink 'em down then blur 'em. Mainly, I'd use the plain black n white ones instead of the color ones so that I can add more subdued colors. If you kept these then the map itself would have to be more colorful...one or the other.