Personally I would not use any form of narcissus because of the excretions which are poisonous to other cut flowers. I would use the following. Forsythia is a given, they are yellow and can be used long and arching, straight, or cut short. Iris for the blue, old fashioned garden iris have a wonderful scent. Hyacinth is another wonderfully scented flower for spring and come in blue and yellow. You didn't say if you could use berries, but if you can I would add some Viburnum Berries, they are also blue. You can also use yellow roses which should start blooming in April (depending on where you live). The following also last at least a week with proper conditioning: Yellow Ranunculus, Purple Lisianthus, Blue Delphiniums, Veronica, and Larkspur. Your Anemones are also nice. I would make sure to include berries and make sure to concentrate on the textures and shapes of the flowers to include a nice variety.
