NBR at PBS is running a series of year end tax tips (link here). My take is in investing, taking gain/loss should first based on the investments prospectus (how you think your investments will work in the future), the tax should be secondary consideration. It is still important because in some cases you want to make sure you have enough cash to pay the tax from tax gain. With this in mind, here is the first video of the series. This one is about capital gain.