(Btw, I found all the TB-suggestions amusing XD)
Akage no Anne - the anime based on Anne of the Green Gables (I only know the Danish title and just roughly translated that) has pretty modest clothes
Sophie from Howl's Moving Castle wears a long, green long-sleeved dress, and I think your face fits her. /also thinks it has a collar but not sure.
Marie Antoinette from Rose of Versailles, but again unsure on the collar thing.
Pokemon - gijinka design for i.e Dustoc and Vespiqueen are quite modest, and with gijinkas you can always tweek the design to your taste
Fuu from Magic Knight Rayearth in her wedding dress, and there's also an illustration where she has a fully covering blue dress with a collar and all on.
Ru/Kraehe from Princess Tutu gets a GIGANTIC dress with long sleeves at one point in the series (The USA team for WCS this year made it, it looks sooo gorgeus http://community.livejournal.com/wcs...09.html#cutid1
) But again, collar-business.
Sharon Rainsworth from Pandora Hearts - AND she has a high collar
Shinku from Rozen Maiden! And Suiseiseki from the same show (it could be that I got the name wrong, but I'm talking about the brunettes with the long green dress... I seem to have an unhealthy obsession with long green dresses?)
Other than that, always be sure to check out artbooks for alternate outfits and such.