JR West regional pass, Green car

Hello. I'm interested in the JR West Kansai-Hiroshima Area Pass for an upcoming trip. An approximate itinerary will be Kansai Airport - Hiroshima - Miyajima - Okayama - maybe Takamatsu - Kobe - Osaka. After that the 5 pass days are up and I'll continue with regular tickets to other destinations to the east. The all Japan pass won't pay off. Also interested in upgrading some trips to a Green car seat reservation. I understand that I will then have to pay both a limited express fee and green car seat reservation fee. However I'm wondering if it still pays of to have a pass and pay extra green car fees, or if I should skip the pass and simply buy regular green car tickets instead? Short distances in second class might as well be paid with IC card anyway in that case, they won't pay of the pass. Also, with a pass, can I reserve and pay the green car seats and extra fees in the ticket machines or online, or do I need to go the ticket office? Time is valuable and I'd like to avoid the ticket office.

However I'm wondering if it still pays of to have a pass and pay extra green car fees, or if I should skip the pass and simply buy regular green car tickets instead?

You will have to make the calculations. If you make lots of train rides, it could still pay off. But by using Green Cars, you would basically wasting a part of your pass benefit (because you are paying the limited express fees, which otherwise would be covered), and more rides would be needed for the pass to pay off.

Also, with a pass, can I reserve and pay the green car seats and extra fees in the ticket machines or online, or do I need to go the ticket office? Time is valuable and I'd like to avoid the ticket office.

You would have to buy the limited express ticket for a Green Car without the base fare ticket. It can easily be done if you know what your are doing with Japanese online reservation systems and ticket machines, but frankly I am not sure whether it is easily done with the English interface of ticket machines. And I doubt that the English online systems allow for it.

Purchasing regular green car tickets (including the base fare) would be simpler.

Hi Uji, thank you for your excellent reply. I checked the JR West online reservation website more thoroughly and noticed that they show the both ltd xps ticket fare and the base ticket fare separately. If I would book many/most of the trips in Green car, the ltd xps fares would add up and together with the rail pass fare, it would indeed cost more than just buying regular green tickets. I'll just have to think about how many regular vs Green car trips I would like.