I love the series, our wedding is actually Harry Potter themed, but the only name I love from the series is Luna, but here are some suggestions:
Harrison - nn Harry
Harrold - nn Harry
Antares (one of the few astrological names JK didn't use)
You could go for the Frederic spelling instead.
I love Hermione, Ronald, Dean, and Seamus! I LOVE Harrison and could see Harry springing from that... :D :D I would love to have a Hermione. DH nixed it, but I keep letting him know I still like it. :) I would nick name her Mia.
How about the name Socorra to add to your list?
Hermione is on my list for future daughters. :)
I think for boys you could easily use Harry, Frederick, and Lorcan without most people picking up on the HP theme. You could also use some of the more not-specific-to-the-books names (James, Charlie, Seamus, Ginny, Lily, etc) and use the more unique obviously HP names for middle names. I would really advise against Narcissa or Bellatrix just because no matter how you intend them to sound they will still have very bad connotations for your kids, however Hermione is such a lovely name I would say to use that regardless of the book associations(plus she as a character has a very positive image for a little girl to be connected with). Some of your other names are lovely as well so I think if you mix and match properly there are a myriad of combinations you could use that wouldn't wind up being HP overkill. =] Other suggestions might be: Seraphina, Saphira, Calliope, or Seren, Lachlan, Emeric.
I don't really have any other suggestions that haven't already been said (loads of great ones!), but I wanted to say that I totally understand and you are awesome :). I know when the time comes to pick a name, you'll know just the right one to pick. And, hey, you can get away with a couple if they aren't too obviously HP. Great lists here so far!
Since Bellatrix is the name of a star, I looked up other star names:
Most of these are pretty unusual, but maybe you'll find inspiration. I selected these from the list found here: http://en.wikipedia.org/wiki/List_of...names_of_stars