Arranging galleries for a website, or for ones own photographic collection for that matter is fraught with danger. There will come a time when the gallery headings affect the way one goes out to photograph the world. They become the monster under the bed.
I used to arrange my images by geography - where the photographs were taken, and that is certainly valid but it tends to apply pressure to revisit places in order to "fill out" the portfolio. Nowadays I prefer to organize by subject matter. I have used categories such as "Flowers", "Buildings", "Streams" and so on but that ends up being an endless list. Now I try to use a more conceptually based organizational style and that works better for me. Of course, being a landscape photographer at heart, the concept of a Land-scape (a view with land in it) will inevitably come to dominate my conceptual list of galleries. Nevertheless, I like the "scape" idea and I now use it a lot. There are some things that do not fit into that pigeonhole however and for these, I fall back to concepts or ideas (well, ideas are really concepts aren't they?). I now have fourteen main gallery headings - that number includes the instructive 'Before and After' gallery. Some of the main galleries have smaller galleries or portfolios within them but if you need something specific such as a group of photographs from one country, you can always do a search and get your grouping that way.
The 2014 website revision is notable for the fact that the number of galleries, sub-galleries and images has increased greatly from what came before. Formerly the website showed 200+ images, now it shows over 600. That's quite an expansion.