From the sound of your requirements, I'd recommend the Parker pens. They are very
practical, a pleasure to use, and not so eye catching. The caps pull off so you don't have to screw them on and off. Refiling is a breeze and quick with the aerometric filling mechanism.
The 149 and M800 would be better for a larger hand, but the piston filling would take a bit longer,
and they're quite eye catching. I don't know about Lamys.