Thanks for the feedback Jordan and Grass4Hopper.
I am pretty much hell-bent on using the blue, but I love the idea of the purple wash between the plates and the skin and I think it will look great. I considered a blue wash for that but never even thought of using the purple so thanks for the suggestion.
For the skin color, I really like the lighter color but it does look less natural and may be a little too close to the 'official' Hive Fleet Leviathan paint scheme. I was considering trying a flesh colored wash to darken the first model a bit and add some subtle shadow and definition where the limbs and such meet, but I will also have to try out the purple wash over the whole body to see how it works out. I'm thinking it might be a bit too much purple for my tastes but it won't hurt to try so I'll give it a shot. Lining the creases with a micron pen might also work but I'm not so sure about that method. I think the wash will be better than lining.
I personally think the red will be too close to the purple and too much of a distraction like the darker blue I also tried but I do like that you're throwing out ideas like that. I did consider a different color for the details but was leaning more towards the yellow/green end of the spectrum. For reference, I have been using the color wheel and information in
Sandwyrm's Color Theory Archive from the blog The Back
40k.
The color I was testing out on the eyes will also be used for other
misc. details on the models like the gun 'eyes' on fleshborers, Hive Guard guns, deathspitters, etc. so the eyes on these 2 models are mostly just to try different colors. The washed eyes could be a really nice touch and would be much easier than painting those tiny little eyes. I'm really digging the wash idea for the little buggers. I could also try a contrasting color wash or paint for both the eyes and
misc. details like the yellow/green to contrast with the purple and blue. I use Les' Wash Recipe from
Awesome Paint Job (there is also a thread somewhere on dakkadakka that you could probably dig up) so I can mix up just about any color wash my heart desires. I could also mix some inks with matte or other medium to get a specific color paint or use the
Citadel Color Mixing Chart that I featured in a
blog post on paint equivalents. Add that to my fairly decent range of paints that I already have and the options are endless. I will just have to try out a bunch of different colors.
All in all, excellent feedback and some great ideas that I will have to try out. Thanks a lot, I appreciate the help!

Any other comments, feedback, suggestions, etc. are more than welcome and I'm always interested in hearing more. Thanks again and thanks in advance for those yet to post.