Brown rice tastes fine if you actually buy real brown rice. The shit they generally sell in the markets kind of looks like white rice that they soaked in mud for a while to make it kind of pale brown.
I think the brown rice you're talking about is a long grain. If you can find a medium or short grain brown rice they generally taste better. Of course it isn't going to be as good as Arobrio rice or good Japanese sushi rice.
In which case you might as well say fuck the GI Index, make some risotto or slap a piece of tuna on the white rice and call it a day.
By the way, if you can find it, black rice is really good. It isn't like that black and brown wild rice--it is jet black, short or medium grain rice. You can find it at Asian markets for cheap or pay a shitload at a gourmet white people grocery store. It tastes really nutty. I've got no clue what the its GI is.