Leaning toward A. It's a chance to see the market, get a better idea of just what social link options are open to us, and possibly overhear some gossip about the Anthros without checking out their park just yet. Not to mention the chance to build up the Rikku social link. She might not be the most useful person to have around, but the more friends, the better.
Alternately, surveying the Anthros without Rikku seems like a good option. Might be dickish to ditch her, but bringing her along would probably be unwise -- for one, she might screw things up, and she's also been established as quite gossipy, and I don't think that spreading information about the Anthros mission would be a good idea just yet. Furthermore, there will be plenty of opportunities to build up social links, whereas this mission needs to be completed as soon as possible.
Also, what direction are we thinking of taking overall? Odessa's organization seems filled with potential allies, but Vercetti's crew also has a chance of providing some heavy hitters. Maybe work toward a potential Al Bhed-Vercetti alliance with the Emerald as a bargaining chip?
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I also think going back to Tifa's bar eventually is worth considering.