Are there any divine spells worth taking as Spells Known for a Sha'ir?

[Luccan]

I know that it's much harder to retrieve unknown spells successfully, but is there even one spell (that fills a gap the Sorcerer/Wizard list does not) that means it deserves a slot on what is essentially your "closest to guaranteed" spells list? Especially considering it takes hours to actually access them?

[Psyren]

I know that it's much harder to retrieve unknown spells successfully, but is there even one spell (that fills a gap the Sorcerer/Wizard list does not) that means it deserves a slot on what is essentially your "closest to guaranteed" spells list? Especially considering it takes hours to actually access them?

The divine spells are almost never worth actually preparing; instead, rely on items like scrolls and staves to access them. As you mentioned yourself, your gen will be gone for 1d6+{spell level} hours PER SPELL to prep them, meaning even if you send it out overnight you're unlikely to get more than one or two, and even then it might still be gone in the morning when you need it to prep your arcane spells.

Instead, your limited number of "spells known" should all be spent on arcane spells so that you can access a large repertoire throughout the day to cover various contingencies. The difference in timing between a known arcane spell and an unknown one is huge (rounds vs. minutes, i.e. you can grab known spells even during combat if you really need to), whereas there is no difference in timing for a divine spell - it'll take hours whether you blew a repertoire slot on it or not. Sure, "learning" the divine spell will negate the -6 penalty, but it's a class skill for you and you're Charisma-based, beating that should still be doable.

[ATHATH]

What the divine spells are really useful for is making the Sha'ir count as both a divine spellcasting class and an arcane spellcasting class for the purposes of prestige classes that advance only one type of them.

[Jormengand]

All that failing to know a divine spell gives you, AFAICT, is a -6 on a check that should be hard to fail. If you have 20 charisma and full ranks, for example, you should have a +10 at level 1 (including the +1 per Sha'ir level) without expending any real resources, like a masterwork tool or Skill Focus (Diplomacy). At 8th level, however, you have a +25, then adding in your masterwork tool and SF(D) a +30. To get a third-level divine spell you don't know, you need a 32. You haven't begun investing real resources into getting hold of that spell yet. If you were tempted by the idea of learning divine spells, you should probably try buffing diplomacy just a little more instead.

As for which spells you might actually use, Divination isn't terrible if your DM is willing to be decent about it. Access to Fire Storm, one of the few fire evocations actually worth casting, is nice but the high retrieval time might rain on your parade a little. Miracle can be handy too, especially since unlike wish it can lack an XP cost. Control winds is neat. What you might want depends on your ability to predict the situation hours in advance, though.