Hi, Russ,
Well everything you talk about doing - setting the picture mode to vivid, using edge enhancement, backlight high, etc. will exarcerbate the worst digital artifacts and make the flaws in the set's technology and processing much more obvious. Although you may find the image "pleasing" to look at, it is not accurate. What I would suggest is taking a look at David Katzmeier's settings for the TV in his CNET review of the LH90. You can find those here:
http://forums.cnet.com/7723-19410_102-349354.html
Plug them into your TV. Leave the settings alone for a couple of days and watch some content you're familiar with: Blu-ray, DVD, etc. The key is that, for those settings to be correct, you really need to control the lighting in your viewing room, so leave the lights low during the "Adjustment period."
Anyway... whatever looks best to you is best, but keep an open mind and you might find that an "accurate" picture is actually better.
Regards,
-Chris