I send flowers nationally (uk) and internationally (mainland Europe, USA, Australia, Singapore, South Africa) all through the year.
Overall, the best flowers have usually been when contacting the local interflora florist directly. Mentioning that I found them accredited through IF but ordering direct can result in varying levels of service. More often than not you get a larger and prettier arrangement for the same money as they're not paying extortionate fees.
Otherwise Google and TripAdvisor are your friend for finding somewhere local to the recipient.
I now actually save the really good florist details in the notes section of the contact for those that we send flowers to as standard. Not only does it mean you don't have to do the same google search time and again, the details are to hand and it's not a chore to accomplish.
Please don't order the delivered in a box by courier flowers. My MiL sends me those for my birthday every year. She orders a lovely bouquet which isn't cheap by any means but by the time it arrives to me (1-2 days from dispatch), everything is tired around the edges and a bit tossled. You can see how lovely they're meant to be, and appreciate the present / thought, but are slightly disappointed by the fact everything is wilted at the edges.