I've been involved in both kinds, either as an attendant or just making the floral arrangements. I LOVE helping couples plan and create their special day perfect, well at least perfect flower wise, I cant help with late catering crews or DJs even though I have been asked (trust me you don't want my cooking or musical selections)
Most brides/grooms have a pretty good idea as to what they want in the way of flowers or at least colours ( thanks Pinterest! also follow us on Pinterest Acanthus floral ) Seasons usually dictate what colours people want, but they don't have to. If you love oranges and yellows, but are getting hitched in June then have yellow orange colour scheme. Its all about what you love, the only exception is flowers being in season. Sure I can get you peonies all year round, but they will cost about as much as your wedding gown in the off season.
Now that I have rambled on, If you or anyone you know is