I have 178 aravenel and love it. Great choice. Don't have 80, but I think I need it. . . .
Ditto on the navy ties with navy suits advice here. For the most part, I wear my navy ties with everything but the navy suits. Black is a classic tie, especially with a lighter than navy/AFB suit. For conservative looks, I usually go dark reds and browns. If I had to pick my favorite tie with a navy suit, it might just be the chocolate fina that stitches has posted a few times. But that color is so striking, it might not be the most conservative choice.
I have worn this one with navy and a white shirt to subdued effect I think. http://www.samhober.com/macclesfield-print-silk-ties/macclesfield-printed-silk-tie-20.html
Frigi, PP is probably the best to help you on the ties your looking at it. Stitches may have worn purple a time or two as well as I recall. Perhaps they can shed some light on any trouble they've had pairing it with shirts. I don't have any purple myself. In my head it seems that purple would easily go with white. For blue shirts, my imagination seems to lead to the more contrast the better. Dark purple on sky blue. The lighter the purple, the harder it will be to wear on blue, especially shades darker than sky or very pale.