To wildly oversimplify things, there are two sorts of tribute performances: the sort that's huge where all the star power and vocal force and staging is amplified to build a departed star a monument worth her legacy, and the sort that's understated, a quiet showcase for the music that made the star in the first place.
Etta James' tribute at the Grammys--in a truly unfortunate bit of timing, only the first the night would see for a departed diva--was of the second sort, Bonnie Raitt on acoustic guitar, Alicia Keys on keyboard and both understated in their vocals. Nor did they choose Etta's obvious song ("At Last," that is), but standard "Sunday Kind of Love," first recorded in the '40s and recorded by dozens of others since. The tone was fitting. It would've been so easy to turn this into a battle of the divas, whether those passed or performing. Instead, all that we saw was reverence.