Cranesbill geraniums form a big flowering clump, attract bees - they're perennial and easy to divide for more plants!
On my shady side I have hydrangea, ferns, skimmia, fatsia japonica, iceberg and new dawn climbing roses, nandina, astilbe, fuchsias, begenia (elephant ears), annual begonias at the front of beds filling gaps, buxus, brunnera jack frost, heuchera, hellibores, climbing hydrangea, euonymus, clematis armandii, ajuga (bugle) and vinca. More than one of each!
It's a great idea to have plenty of evergreen shrubs for winter interest.
Do you have tall boundaries (fences, walls)? If so it's a good idea to get some climbing plants in as many can take 2-3yrs to establish. As well as the above I have passionflower, ceonothus, star jasmine, evergreen clematis (freckles), pyracantha and buddleia on my sunny fences. They all tend to keep their leaves over winter (Herts). The buddleia is a thug and needs keeping in check after flowering 
Acers are lovely structural plants and come in many colours. They lose their leaves over winter.
A tip I've heard many times is to buy two or three of each shrub. Your borders fill more quickly and you end up with a rhythm/ repetition as you look out across your garden. Obviously you might not want to do this with every plant but it's a handy way of filling space at the start.