Buzy lizzie or petunia maybe.

How about Geraniums, many have variegated leaves as well as different coloured flowers. Try to avoid the colours clashing. You will probably need some spot plants to give height, these can be Geraniums and edging should it be an all round bed, one of the dwarf varieties of Geraniums.

I like that idea Dr Bob-- I do like hardy geraniums-- given a' haircut' after flowering they bloom all summer, you could underplant with crocus for a spring show as well

Penstemons - Usually grow to about 60cm so will give you some height and come in a range of colours from purple through red to white. They are quite hardy and being perennial will come back year after year.

This must be an exam question - we had it a few weeks ago!

Salvias are good - ranging from white through pink to blue, mauve and purple. Even red if you add a few annual ones in!

I like Eschscholzia (California poppy). Sow by scattering, they bloom all summer, and at the end you pull them out and the seeds are already there for next year.

funny you should say this I was thinking the self same thing spritz.
if they said so it would be easier to advise.