or even a bed of Blue Wedgewood Iris,
or both!
I think Celosia are fairly close in height to the Moonbeam Coreopsis, so I'm not sure if it would work in front. But...bet you could do some realllly neat things by making stripes of one and the other, or planting one as a border to the other. Or is that kinda what you meant?
Could certainly look nice! Lotta color.