You are right, you don't need a 7-day or longer pass. Your best routes are on JR, so you can uncheck Private Railway on HyperDia for your travel from Nikko on.

Your fare from Kurashiki to Kyoto would be ¥ 8,380. You could get a 5-day Kansai Wide area pass for ¥ 9,000. You could use it to get from Okayama to Kyoto and for day trips from Kyoto (Arashiyama, Nara, Himeji, Osaka, Hikone, ...).

You could buy a ticket from Takayama to Shin-Osaka and use the KWAP from there. (or Takayama to Kyoto or to Maibara)

I don't know if you are interested but there is a Wide View Hida L'Ex from Takayama that goes all the way to Shin-Osaka and Osaka, via Kyoto. It departs around 3:30 PM. It is less expensive and slower than the shinkansen route. It stops for 7 minutes or so in Gifu.

mrwunrfl -- "Your fare from Kurashiki to Kyoto would be ¥ 8,380. You could get a 5-day Kansai Wide area pass for ¥ 9,000. You could use it to get from Okayama to Kyoto and for day trips from Kyoto (Arashiyama, Nara, Himeji, Osaka, Hikone, ...).”
Should I just wait and get the pass when we are in Japan? The savings is just a couple $s to buy it online now. Then we would have to exchange it when we get there. Do we need seat reservations? It says we would need to buy them extra.

Two drawbacks to the KWAP: it doesn't cover the Tokaido shinkansen and doesn't include reserved seats.

The shinkansen restriction means that when you go from Kurashiki to Kyoto you would have to get off the shinkansen at Shin-Osaka and take a JR rapid, local, or limited express train to Kyoto.

JR fares, on a limited express or shinkansen, include the base fare and a limited express surcharge. The seat charge is in addition to that. For you to get a reserved seat with that pass means paying the surcharge as well as the reserved seat charge.

The surcharge shows up in the Seat Fee on hyperdia. Do a search for Kurashiki to Kyoto and look on the line that has the shinkansen name. To the right is a dropdown that shows a price of Green, reserved, and unreserved. By default it shows reserved. The difference between that and the unreserved is the cost of the reserved seat.

Here is the fare that I mentioned above:
Total:¥ 8,380 (Fare:¥ 4,000 Seat Fee:¥ 4,380)

To compare with the pass, I should have given you these prices which don't include a reserved seat:
Total:¥ 7,340 (Fare:¥ 4,000 Seat Fee:¥ 3,340)

That 3340 is the surcharge. The price difference of 1040 is the cost of the seat reservation during high season - which includes today.

The actual value of the pass for your trip from Kurashiki is even lower. To get the equivalent travel you would pay
Total:¥ 5,830 - Kurashiki to Shin-Osaka un-reserved
plus
Total:¥ 560 - Shin-Osaka to Kyoto on JR rapid

So, that one trip doesn't get you close to the cost of the pass

Unfortunately, none of the JR West passes cover the bullet train between Shin-Osaka and Kyoto - just not part of the Sanyo shinkansen. If they ever do any changes, that is sorely one area that needs it.
But the pass does let you use the limited express trains, like Haruka or Thunderbird, and that is what I aim for - especially during morning or evening when the rapid trains are crammed with commuters. I find it excruciating when a rapid train goes half way, and then becomes a local train stopping at every station for the rest of the way.

Glad you enjoyed your trip!
Sometimes it's difficult to figure out whether a pass is worthwhile or not or which one to purchase. I go through that also.

But maybe you mean the 'seat fee' which is not really the cost of reserved seats.... It's more like a required express charge.

For example a Nozomi train fare from Tokyo to Hakata/Fukuoka totals ¥23190 - the fare is ¥14,080 and the 'seat fee' for reserved seat is ¥9110. The seat fee for an unreserved seat is ¥8140 so less than ¥1000 (around US$10) difference to have a reserved seat.....this is a five hour trip across country more or less...

I'm glad (but not surprised) that you enjoyed Japan. Thanks for letting us know!