I was really aiming for the dead of winter in my choices. Currently I have quite a few clematis - there is a lovely shrubby one called 'Wyevale', absolutely beautiful, with masses of curly light blue flowers. Masses of hardy chrysanths, quite a few roses, late salvias are the x jamensis varieties, fuchsias, rosa The Fairy keeps on going until Christmas easily, phloxes as long as they are in shady areas, asters of course, buddleias, perennial erysimum 'bowles mauve' which flowers all year in sheltered areas, solidago, rudbeckias, geranium 'rozanne', hebes, Japanese anemones, trachelospermum jasminoides is fully out and the ordinary jasmine is out again too, and that is just what I can see from sitting here. Oh and that red or white stuff that grows all over walls that I can never remember its name. Valerian, that's it. As well as the sedums.
Most nurseries will try to sell anything they can while it's still in flower or looks good from a foliage point of view. It's worth visiting one each month to see what they have.