Many gardening books have lists showing what is in flower by season. Alteratively visiting a garden centre every month for a year will show you what's in flower .

For plants with a very long flowering season try this blog I produced with the help of other GOY members which has lots of photos and cultivation details

http://www.growsonyou.com/anchorman/blog/12681-plants-with-a-very-long-flowering-season

When you've done that Paul go to the alphabet at the bottom of this page, choose B, then border ideas and you will see other members ideas as well