You can't hardly go wrong with what's in season; to me, the most fun spring flower is Daffodil.
If you aren't sure of your colors, you could go with neutrals for your wedding party and really bump up the color with your flowers. That would be gorgeous!
Spring Wedding Flowers in Season
Anemone * Blue, red, pink, white * Jan-May and Aug-Dec.
Bells of Ireland * Green * January-October
Boronia * Pink * April-May
Casa Blanca Lily * White * January-October
Daffodil * Yellow * January-Early May
Delphinium * White, Blue * April- October
Hyacinth * Purple, Pink or White
Lilacs * Violet or White
Narcissus * White
Peony * Pink or White * Late Spring Early Summer
Ranunculus * white, pink, red, orange and yellow * February-May
Star Gazer Lily * Pink and White * January-October
Sweetpea * white, pink, red/coral, and lavender/purple * December-May
Tulip * Many colors, including white, pink, yellow, red, and purple * December-April
Waxflower * pinky purple and white
The bright colors photograph beautifully, and look amazing on Metallic paper! Most importantly, just have fun and use what you like!