I've always liked colored lights -- I suppose because that's what I grew up with -- but my wife convinced me that all white lights were the way to go -- even on the tree (and silver and gold ornaments only!). It probably does look the most elegant, but I may have to convince her that our kids will find all of this a lot more appealing if it's colorful.
The outside of my house is done in all white lights, that's what I prefer, but I make a concession with the tree inside for the kids, that has colored lights on it.