I like things like titles, of course. So, each tier needs the appropriate title. Second tier could also have a unique weapon and an emote. Top tier would have all those (though, different weapon and emote) plus a mount. The top 96 players, as mentioned, deserve something truly special... like a new companion.
For a weapon, I'd love to have blasters that shoot lightning.
Emote could be posing/waving /.signing autograph for your adoring fans. If you wanted to do a regen item, lifting weights or taking target practice would be good ones.
Not sure who a new companion could be. Maybe it would be a rodian character or something.
I also just thought of a possible pet for tier 1. Pet could be a holo of Giradda or Baron Deathmark that follows you around.