Is there any way to get favored results from this spell? I've heard folks say this spell is a must have for sorcerors, but it seems too random. It's almost like a wild mage's dream come true. Is there a way to guarantee the rest option?

Wish is always random. A higher WIS just means that you have a better chance of getting a good result. 18 WIS grants you a 12.5% chance to get the Rest&Rememorise option, IIRC.

Yeah, higher wis is pretty important with this spell. Usually I line up my cleric between my mage and where the spell will be casted so I can have my cleric do the talking. Something like this:

Wish Genie
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Cleric
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Mage
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Rest of the party

Potions of insight can help too (they're not good for much else).