Rhodo luteum is yellow and has a fantastic scent, it is deciduous and grows to 8ft or so. There are so many to choose from that you need to narrow it down to size and flowering time...same time or following on from each other? I hope that you have the right sort of soil?

Take a look at the site below Scotkat masses of rhododendron photos and if you click on one you get all the info

http://bit.ly/mQziaA

Thankyou Volunteer and MG ,I cant get into the site you gave link to MG.

Volunteer's luteum, a similar looking lutescens and Yellow Hammer are all nice yellows. The latter has flowers for a long time and is about a meter tall.

Here is the horribly long link.. you will need to copy and paste into your web browser

http://www.google.co.uk/search?q=rhododendrons&hl=en&client=safari&rls=en&biw=1150&bih=668&prmd=ivns&tbm=isch&tbo=u&source=univ&sa=X&ei=Auj4Te-3Gc2r8AO7k8XHCw&sqi=2&ved=0CJIBELAE

I have a deciduous Azelea Luteum and the bugger has never flowered in the two years I've had it. It's putting on lovely new growth and foliage though!
I also have a beautiful Rhody - Dreamland - it has pink buds that open up white. Stunning plant.