Yeah - Marriott claims to be 60km from KIX:
http://www.marriott.com/hotels/maps/...naruto-resort/
That's dishonest. Actual distance by road is roughly 180km.
The Marriot voucher will not save you money and it will be a pain. I recommend that you go to Kyoto as soon as you arrive.
Tip - Buy a one day Kansai Area Pass when you arrive at KIX. This will save you a few yen:
http://www.westjr.co.jp/english/travel/jrp/index.html
Cost of the pass = 2000 yen.
Pass lets you ride the Haruka train to Kyoto. (Normal cost = 3,690 yen)
It is not always easy to find accommodation in Kyoto. Reserve early.