Jason, I took the first 2 photos into the LAB section of photoshop where you can really dig deep into the colours and white balance. Using the white areas as a starting point, each picture got a light change in colours to get perfectly neutral, but certainly nothing obvious, and the originals are definitely within the realms of looking natural as they are.
The only minor differences were the first was carrying a bit of magenta in the neutrals, and the frog, when 'neutralised' actually looked worse in my opinion, the greens went too yellow.
Thats all a bit technical, but what it showed me was that your originals are pretty close to being bang on in my opinion - natural colours
Hope that makes sense and helps a little
Mike