You are right that Okayama does not have much attractions downtown, but it is one of my favorite places since it is a good "transport hub" with several attactions a train ride away.

• Kurashiki to the west as you already mentioned, it is not that big so you can see everything on a day trip.
• Naoshima art island in the seto inland sea can be reached by ferry from Uno to the south.
• Bicycle rental at Soja to the west to cycle on the Kibi plains.
• The Matsuyama castle in Takahashi to the north.
• Marugame on the Shikoku Island to the south.

So actually I would choose your first itinerary.