Aang: All this time, I thought firebending was destruction. Since I hurt Katara, I've been too afraid and hesitant. But now I know what it really is... it's energy, and life.
Zuko: Yeah. It's like the Sun, but inside of you. Do you guys realize this?
Chief: Well, our civilization is called the Sun Warriors... so yeah.
Zuko: That's why my firebending was so weak before. Because for so many years, hunting you was my drive... it was my purpose. So when I joined you, I lost sight of my inner fire. But now, I have a new drive. I have to help you defeat my father and restore balance to the world.
Fire IS destruction, but it is ALSO energy and life. Fire is the most numinous of the elements: where the air is always there, and will simply move to and fro, Fire has a heartbeat, and it can be dispersed to never return again. Fire, in the abstract, perches precariously on the point between destroying and being destroyed.
So what would Fire want? It depends on which part of Fire you want to talk about. Is this the Fire of destruction, which seeks to consume everything? Or is it the Fire of need and drive, which seeks to be sated, which yearns for some particular thing? Or, perhaps, is it the controlled Fire, that which sits at the fulcrum between wanton and needy, the fire that mirrors the metabolic fire that burns in each living thing?
If it is the Fire of Destruction, then its desires likely lie in two directions: overcoming something which opposes its expanse, or destroying something particularly important or meaningful. If it is the Fire of Need, given that this is a very powerful fire elemental, I would expect its need/drive to be something that cannot be easily achieved in whole, but any gift which progresses toward that need in a substantial way would be perfect. For instance, if its burning need is to reclaim a lost fortress/artifact/etc. from the forces of the Plane of Shadow, then trophies of defeated shadows (proving that its enemies have been weakened) or items which could enhance its ability to fight shadows would both be highly welcome. A Fire of Balance would be most likely to appreciate the "finery" type things--being in control of itself and its needs means it can pursue higher callings. The example of rare (presumably aromatic) woods is a good one, but also oils, candles, etc. And it might even, possibly, want things that CANNOT be burned, so it can continue to enjoy them repeatedly. Imagine a fire elemental with a scholarly bent. The flimsy, easily-destroyed records of mortals would almost surely vex it greatly, and if you had a rare book transcribed onto stone or metal tablets (which fire cannot easily burn), such an elemental would surely be very grateful.