In comparison to the scale of the convention centre, the marina/seaplane terminal will hardly be noticeable even with its miniscule "ancillary buildings". The only thing that may be taken away from is the view from inside the convention centre (which few of us will ever see again), and even still, tourists LOVE watching the seaplanes takeoff and land so it may only just add to the whole experience. I'd also agree with jlousa that it will only add to pedestrian traffic in the area. There are always people walking to and along the seaplane terminal docks... like all the people walking down to the floatplanes in this pic of mine from February:
Threaded Mode