Fast growing hedge ideas

Looking for ideas on a fast growing hedge. While I love my Neighbours to bits we still want privacy which the current 4'ish fence doesn't. Not really keen on 6' fencing but was thinking along the lines of a willow screen initially, plant a hedge then when the screen has gone past its best the hedge will be up at 6' ish

Ideas???

 

The problem with fast growing hedges is they need a lot of trimming Rob. The fastest I can think of are Leylandii and Grisilinia but I wouldn't recommend Leylandii to anyone, it can create a lot of damage with it's roots to drains and house foundations.

 

Have a look at this thread which is asking for similar ideas