OK, as suggested by
ofankoma, I'll give a bit more detail about my SSHG preferences than I did in the exchange prompt. I'd like to emphasise, though, that none of these are deal-breakers. As long as it's well-written / competently executed, I'll probably love it. I'm pretty sure that I've got plenty of favourite fics / artworks that according to my preferences I really shouldn't like! So treat this as a sort of inspirational guide rather than a rulebook....
I love humour, especially the subtle, ironic, witty type. I'm not asking for a work of comedy, but I do like the odd lighter touch. Some of my favourite non-HP things are Buffy, Chuck, Terry Pratchett, Jasper Fforde and Douglas Adams. If that helps at all.
I generally prefer a more mature Hermione, at least a couple of years post-Hogwarts. In terms of visuals, I'm fine with EW as Hermione, though she's possibly a bit on the elfin side. I don't understand how Hermione's bushy hair often mutates into luxuriant curls in fandom, but my hair's straight, so maybe I just don't get it!
Snape. Hmmm. I've adored AR for many years, but really you have to knock a couple of decades off him to be right for DH-era Snape.
In terms of other characters, I love Luna. And Neville. The Malfoys - I can take them as recently reformed, but Lucius in particular was a genuine bastard in canon. (I do get side-tracked by Jason Isaac's eyes, though.) I like Draco when his character's convincingly explained. I think Ron often gets a raw deal - he's maybe not the sharpest tool in the box, but his heart's in the right place. I do enjoy fics where some of the minor characters (Flitwick? Xeno Lovegood?) get fleshed out.
I prefer canon-compliance as far as possible. Except for the bloody epilogue. And Snape dying, naturally.
I enjoy seeing SSHG's relationship developing, but I'm less keen on estabished relationship fluff. I've been married for more years than I care to remember and have 2 children, so any SSHG marriage / kids stuff has to be brutally / amusingly honest rather than rose-tinted! (Old cynic alert!)
I think that's it, really! Hope this helps someone!! Honestly, though, I have pretty eclectic tastes and will be profoundly grateful for and appreciative of anything that is created for me.