Group of Tolleson's Weeping Junipers

Your selection of plants sounds great but as far as planting all three junipers in the same bed or vicinity I would disagree. Because the weeping juniper is so large and dramatic it should be the focal point or the main speciman of the bed. More than one of these plants would just compete with each other for dominance and you lose the focus of the bed. Unusual plants are much better used as focal points.

I like kidney shaped beds better than crescent as they look more natural and are usually wider to give a better depth to your bed for planting. I dislike planting on those skinny little ends on a crescent shaped bed.

A bench would be nice, just don't put it in the middle of the bed as that just looks too "perfect". Also consider placing your bench where one actually might sit to enjoy looking at something, ie a view, a birdbath, which makes the bench more inviting and useful. I like seeing various sitting areas in a garden. So many views of the garden can be enjoyed as the garden is three dimensional and there are more views than the one from the deck!

Hope this helps.