Which yellow cut flowers last longer?

I work for a store and yellow and white are the company colors we use cut flowers but end up buying them sometimes 2x-3x a week and I wanted to know what yellow and/or white flowers except roses (the owner doesn't like roses) last longer and stay pretty longer. We've found hydengea last a long time but zinnias droop shortly after buying them. Also flowers that are readily availible at flower markets would be good. Any advice would be helpful.

Which yellow cut flowers last longer?
Hmm. I think water plants live longer as cut flowers. Could you try a Yellow Flag Iris?


Here are some pictures:


http://images.google.co.uk/images?source...