Another art question, huh?
Ugh. I have no idea.
As with Question #5, this one is hard to answer as lots of games do a pretty fair to good job of this.
Take into account the fact that I play a lot of IP based games, and I have to say my opinions on the matter are biased at best. Most licensed games use concept art, and photos taken directly from the TV show, movie, or comic they are based on. Instant inspiration if you are enough of a fan of that thing to have purchased a table top game based on it.
Did the FASA Star Trek RPG, or West End Games' Star Wars have good interior art? You bet your booty they did. They had stills from the things they were based on.
A lot of games could use some help in this regard. Teenagers from Outer Space, Mekton, and many Superhero RPGs should be ashamed. Games based on visual media that don't have great visuals are annoying at best, insulting at worst.
Spend 15 seconds on Pinterest, or DeviantArt before making your game and hire one the bajillion talented artists. I know the guy a few desks down is your pal, and you guys built this game together, but damn it, he can NOT draw in a style even vaguely reminiscent of Anime, or Manga. No. Just, just no.
Also, I am a fan of Japanese Anime/Manga art in many of its various interpretations, as well as a collector of Japanese table-top RPGs. While many of the latter don't have as much art as you'd expect, the art is always amazing, inspiring, and perfect for the product utilizing it. I am biased, but basically I am saying that some of the most inspiring interior art in an RPG product I've ever seen is probably in games a lot of people have never heard of here in the West.
Where was I? Oh yeah, most inspiring art...you really got me.