Sounds like massive overkill. All for something that, by chance, can go wrong (i.e. one of the flights is delayed).
I also think convincing FAs to do all that extra work...good luck. Finding a space for flowers, announcing it, handing them out...it's just not in their job description. Unless you were personally friends that that particular crew or at least 1 person on the crew, I think it's very imposing of you to expect them to do all of that.
Same with the GS agents and other passengers. I would find it to be super imposing to make such a request of others, and can't believe GS even entertained your original idea/call.
Imagine the slowdown as passengers are either handed flowers on the way out, or prior to getting their luggage. Flowers can leave a mess on the plane, on the jetbridge, etc. Plus, what if someone's allergic?
I think you should find a different idea for this proposal that doesn't involve a plane full of strangers.