I used to have the JBL E100's (a slightly larger version of those Venue series). They were good speakers. They are a little dull in the midrange and in the highs (although a slightly bright amp takes care of the highs). The bass was great. I ended up selling them because they were too large for the house we bought.
The Athenas look a lot like the Energy C line (same parent company) which I have heard are really nice. I'd like to hear some reviews of the Athenas. It's a good price none the less.
Also, for 300, you can get the PSB B25s (in maple

) which are fantastic
here. Also check
these (Monitor Audio Bronze B2) out. I was impressed by those when I was auditioning a while back. Both of those go down into the ~42-45 Hz range and sound very full for a bookshelf. I've heard floorstanders that don't sound as full. Again, these are just my opinions....
I know you said you want floorstanders. I went exactly that route (in about your same price range) about 2 years ago, and I just sold my JBLs and bought new speakers last month......

YMMV however....