Matt,
Nice work. You're well on your way. Agreed with Mike, need to shoot at sunrise or sunset.
A pro circular polarizing filter is next on my purchase list, too, along with some very specialised filters. I'm going to try and push my photography to another level.
Also, that monochrome image is not HDR. It is a long exposure image. Judging by the water, about 1 second.
Regards,
Humayun