Tommy, given adequate light and room, most any upright cultivar will work for that. Planted close enough together, and this will vary depending on which cultivar you are working with, I see no reason why pretty much all of them could'nt be used this way.

Maybe the thinnnish-looking ones you saw were in too much shade.

+oM

any that grow to the height you want..

its more about how far apart you plant them.. as to a screen block

w/o pix of your thin ones.. it is usually that they were planted long ago.. and in the intervening years.. deciduous trees have overgrown them.. causing the shade tom alludes to ...

ken