Look, do some math with me. An ordinary 21 day pass is 57,700 yen. 21 days is the longest term they sell, so if you wanted another 14 day pass for the rest of your trip, add 45,100 yen to the cost, for a total of 102,800 yen. That breaks down to an average of 2,937 yen per day on the passes. At 91 yen = $1, that means $32.28 each and every day, or a total of nearly $1,130 just for the train passes.
Trust me, staying in the Kansai area and seeing the sights around there will NOT cost you that much every day. You can generally figure about $10-12 per hour of riding the train, though that can vary somewhat (more for express trains, etc). But as a rough guide, do you plan to spend a minimum of 3 hours a day, each and every day, riding the trains? Kyoto is about 45 minutes from Osaka by train. Nara is less than an hour too, I believe. Koya-san is 90 minutes, but uses a non-JR line and so the pass wouldn't be valid anyway. Himeji has a Shin-kaisoku express train that makes the trip in 1 hour for 1,450 yen, which means paying for a round trip to Himeji and back on an express train is still cheaper than a day on the JR rail pass!
Unless you are leaving the Kansai area or taking the bullet train, don't waste your money on the JR pass. While you may come close to breaking even compared to buying tickets on a few days, many other days you'll spend walking around a city seeing temples and sights and hardly use the train at all, but you're still paying for that day with the JR pass.
JAPAN RAIL PASS types and prises
Himeji travel guide - Wikitravel