I have not been to any of those shows, but have heard that the Boston show is really good. I also usually head out to the NY Botanical garden for the Orchid show in February - always a great hint of things to come.
On a much, much smaller level, there are the flower/landscape displays that Adams Fairacre Farms put on, in their three locations. I always like them, as they are very small but very cosy and intimate.

Spring is *almost* in the air !