Couple of tips I've picked up...
I've used the RegEdit hack to go in and turn on the mipmapping (currently at 3) and upped the bitmap from 1024 x 1024 to 1536 x 1536. I'm capping consistently at 29 FPS using FRAPS (which is the self-imposed cap by the game).
I can't turn on all effects, you should leave shadows on normal. Otherwise it gets really choppy in the cities or with a lot of characters on the screen. Otherwise everything is cranked.
The only thing that I'm noticing, is what appears to be a redraw issue when panning around the screen. The framerate is still capped, so it's a software issue of some type. I don't think FFXI was ever intended to run at 1680 x 1050, but I'm going to play with the setting a bit more.
Any other tips or tricks people pick up, I'm interested
-Ten