Pburgess - in the end I decided not to bother with the watch straps. I wasn't worried about them being too thin, as much as worried about how they would feel and how it would look when done up. Instead I added two more little leather flaps and some heavy duty snaps to keep it done-up. The way I've done it makes it sort of 'modular' in that I can always remove the two flaps with the snaps, and replace them with some other closure method.
At the same time I swapped out the dark hardware for bright brass, and added brass grommets as a bit of protection and to clean up the apertures for the light sensor and the humidity sensor. Still have to make some sort of bezel for the screen, though.
Skewworks - thanks for the comments! I don't actually know what a Pipboy is, but I've heard the name. I gather it's from a movie or tv show or something? The flashlight was a last-minute addition but it actually has proved quite handy (sorry for the pun!) It's not crazy bright but it is enough to make sure I don't walk into walls or furniture if I'm moving around the house with the lights off.
Good work on the C# GPS driver! I'm using a very stripped-down version of TinyGPS. I had to eliminate anything that wasn't being used, as ram and flash were getting very tight.
Updated front view: