Know and love all of those except I'm not familiar with Nielson, but my gf is, so she will beat me up for that.
I love Leyendecker and bouguereau
I got my Big Leyendecker book from Stuart, I always have to be careful when I go to his store, soooo easy to spend all my monies!!!
Egads! If I had to list all of my sources of inspiration I'd be here a month from now still compiling the list! 
Not that I'm an artist by any stretch...
But I'd have to toss out Boris Vallejo and Hajime Soriyama as two of the artists that I've ALWAYS thought were the top of the game.
Oh yeah. Vargas. Can't leave out Vargas.
"City of Heroes. April 27, 2004 - August 31, 2012. Obliterated not with a weapon of mass destruction, not by an all-powerful supervillain... but by a cold-hearted and cowardly corporate suck-up."
Love all 3 of those, especially Sorayama. 
You know, I had a thought... I know where my inspirations come from, but what inspires other folks. I'm sure there was a thread at some point listing them, and that most of them had to do with other CoX artists (no offense you guys) but I wanna dig deeper than that.
Part of this is actually part of my BFA paper to graduate, so I'm actually killing two birds with one stone research wise
So...here's mine (with links):
Claire Wendling: I've known about her for some time, but she's only recently been imported to the US. Her earlier comic work is vastly different than what she does now. Claire Herself
Where I get my Claire Fix (and a few beautiful examples)
Alphonse Mucha: The 'Father' of Art Nouveau
Salome: An example of Mucha's work
Hayo Miyazaki: Master storyteller and artist
Miyazaki on the Web
Beatrix Potter: Weird note, when I was young, and during women's history month at school, I would often dress up as Beatrix and speak to students about her life and work. Her watercolors always inspired me, and I tried recreating her work quite often as a child. Not only that but she made it alright for me to sit around drawing dead animals as a kid.
Beatrix Potter at PeterRabbit.com
Dean Cornwell: Dean of Illustrators This man could PAINT. You don't see people painting like this guy, or NC Wyeth or Howard Pyle anymore...sadly.
Dean of Illustrators
Brandywine Artists: NC Wyeth, Howard Pyle...
Howard Pyle: One of his many pirate paintings
NC Wyeth: Robin Hood
Golden Age Illustrators (Arthur Rackham, Edmund Dulac, Kay Nielsen): I grew up on illustrations like these thanks in part to my aunt. Again, watercolors. I love watercolor, and if I could do watercolor like Dulac did, I could die a happy artist
Arthur Rackham: Fairies piece
Edmund Dulac: From 1001 Arabian Nights
Kay Nielsen: Not the best image...but beautiful still