Where are you? What grows in NH, Seattle TX, Or FL would be very different for this use.

Also, asking this in the shrub forum may get better suggestions that here since this is a plant question rather than a landscape design question.

http://forums2.gardenweb.com/forums/shrubs

Narrow space (less than 2 foot)

Medium to tall (4 to 6 ft)

==>>> there isnt much of anything in shrubs... that is going to get to that height.. but only that wide .... except for a few fastigate forms of say.. holly ... otherwise you would be signing up for a lifetime of pruning it into shape .... which may or may not be approved ....

i dont know what a cool color is .... as you use it ...

welcome to the forums... as noted.. we need big city name at least ...

and being visually inspired.. i would prefer a pic of the spot for best suggestions ...

you can insert a pic in reply post using the camera/photo button below the box you type in ...

ken