All types of artwork are interesting to me, actually. My interest doesn't stem from awe of the artistic merit, or anything of the sort. Instead, I find myself drawn to it because I'm always curious exactly how representative of the music the artwork is. We get an idea of what an album might sound like before we hear it, not in terms of genre but overall mood. For instance, one example of an underlying mood in album artwork is Amia Venera Landscape's The Long Procession, one musical journey that's as desperate as it is unrelenting.
Immediately, the listener's left to think about industrialization and how it's altered the world around us. My hometown's now packed to the brim with supermalls and shopping centers, things that ultimately make us more miserable (but that's for another reverie, I suppose.) However, we're able to reflect upon our own experiences in able to appreciate the journey the album provides us.
Some may say powerful music doesn't need interesting artwork to back it up, the music should be self-sufficient if it's as truly high-quality as we claim. While this argument does make sense, it's also true that my personal experiences through album artwork have immensely shaped my perceptions of music for the better. Of course there are times where less impressive artwork has led me to value the music less, but overall I've ben left with much more positive opinions on albums which have great artwork. The two seem to go hand-in-hand a lot of the time, especially because artwork is an opportunity for the musician to express her interests through tangible imagery. If the music's fairly straight-forward, the artist may prefer minimalism (see Sigur Rós's ( ) for an example.)
The music might be pretty complex, in which case the artwork is more thorough (like The Dillinger Escape Plan's Option Paralysis.)
Both album artworks are representative of the music's mood, without revealing too much about the journey. And both of them succeed precisely because they balance the fine line between ambiguity and clarity.
The album artworks which have stuck with me over time are the ones that have accomplished these two ideas, hinting towards album themes without spoiling them. It seems more musicians are starting to understand the importance of memorable artwork, too. After all, it's necessary for them to stand out. I've browsed through albums on RateYourMusic so much, only to not see anything really catching my eye - and this is something that can be changed with an eye for detail, and for flavorful design. Maybe that's why I'm going into the field myself.