Are't you concerned with a potential image theft, given the large display size? For instance, 1600 px, with a careful interpolation, would be enough for a perfectly usable and sellable 20x30 canvas.
Thanks for the feedback so far.
Slobodan, yes image theft is a concern. Limiting image size is one way to reduce the problem, but I also want to make a statement with my photos, so I need to find that balance point. 1600px is large. I can limit it to 1280, 1024 or 800px. I find 800px small on a large monitor, so perhaps 1024 would be better.
Peter - I know what you mean about just looking at a slideshow image and it's gone, but hopefully it will entice users to choose a gallery for more concentrated viewing.
Russ - another trade off, unfortunately. The other option is to use an opaque header. That may be the route to go. I do like the transparency, but can't find a way to change it. I was hoping that leaving as is would cause people to keep looking at the photos a moment longer, but perhaps not.