Neither Nandina nor hydrangea will appreciate strong wind - Nandina needs a sunny, sheltered spot, and the hydrangea a sheltered but more shady position. If you want a specimen shrub that tolerates wind, here's a list of wind tolerant plants: Tamarix, Berberis, Acer (but not Japanese/palmatum varieties), Ilex, Kalmia, Caragana, Corylus, Crataegus, Prunus, Ruscus, Sambucus, Salix. All of these are larger plants, over 5 or 6 feet or more.

I bought 3 Nandina domestica 'Firepower' a couple of years ago and have been very disappointed in them. They're planted in 3 different places, but not one of them has reached 18 in height. If you want a centrepiece, almost anything would outshine it.
Of Bamboo's list I like Tamarisk and Sambucus, especially one of the black leaved varieties. And I'd add Viburnum opulus to the list, or V. tinus if you want an evergreen.