Hi Eric
The Cistus are lovely plants, so thats a real good choice.
Heres a couple more, but you will have to do a wee bit of research to see if they will suit your soil:
Have a look at Pauls website (produced with the Web Page Generator you'll see discussed here a lot
)
http://www.ideasforgardens.net/meredith/Blooms_Plants/Polemonium caeruleum 'Brise D Anjou'
Its "evergreen" so bears that striking variegated foliage all year round. I have it in my own rose bed.
If you want colour, I'd recommend any variety in these favourites of mine:
Penstemon - Hardy as nails, reliable and lovely flowers over a long period in summer
My favourite 'King George'
Fuchsia 'Genii' - Hardy, lovely foliage and flowers for a long period
Try and find a spot for this
Salvia × jamensis 'Hot Lips'
Its a real beauty and lowers for months
The next two are a little bit tender, so Anthea may have to take cuttings each year to keep them going.
This one is very easy to root up from cuttings
Argyranthemum
Theres a wide range of colours.
My favourite is the pastel yelllow 'Jamaica Primrose'
Osteospermums are firm favourites of mine and may be a nice addition.
http://www.osteospermum.com/They flower all summer. You'll find some varieties which are hardy. Even the tender varieties can overwinter some years. Surprisingly, after this this hard winter, I have quite a lot which are hanging in there very well!
For "bones" of the planting, its hard to beat the Euonymus
The popular Euonymus fortunei 'Emerald 'n' Gold' and Euonymus fortunei 'Silver Queen' look good all year round and would work in a planting scheme. No flowers of significance of course.