When I went last September I spent a little over 2 weeks.
I can no longer say exactly how the itinerary went
1 - 3 Nara
4 - 7 Isobe (Ise, Toba, Anori)
8 - 9 Kouyasan
10 - 13 Osaka (trips to Himeji, then Kyoto)
14 - 17 Kyoto
I think a week would be far too short.
My mistakes were allocating too much time to Osaka and not enough to Kyoto.
I didn't really like Osaka. Another crowded concrete city. So I just got the train to Kyoto each day and was much happier than trying to figure out Osaka. It was also a mistake to stop off in Osaka on the way to Kouyasan.
Although I stayed in Nara I think I could have gone there by train from Kyoto or Osaka. (even if you don't have a rail pass local trains are cheap and efficient)
I also overstayed Kouyasan slightly as well; spending two nights there when 1 would be enough. (bring bug repellant for the mosquitos)
The other thing I found that travel days between locations were more or less lost in an odd way with checking out and in and lugging bags about etc. When I go again I think I'll just try to base myself in one place.
What I did do in my side trip to Kouyasan was to leave most of my luggage at the hotel I was in and was coming back to and just bring a small overnight bag. (Boy you go through clothes in the sticky mushi-atsui weather. Next time I want to pack less and find a coin op laundry) The hotel seemed happy to store it and it was waiting in my room when I returned. (If they hadn't I'd have stored it in a coin locker at about 400yen per 24 hours)
You could easily spend a month in Kyoto. Although you might get a bit templed-out. It took me a while to realise that unlike European cities there wasn't a center as such and all the sights tended to be on the surrounding hills. (Check out Google Earth before you go to see where things are.)
I also went to Ise. I really enjoyed the more rural Japan. However I was visiting a friend and without their help (and car!) it would have been very difficult to get around and do things.
I booked ahead from the UK for accommodation. I could just see myself wasting so much time and energy otherwise but maybe it restricted me once I got there. (Still not sure if my Japanese would be up to the task of finding a place to stay each night. )
Cost wise. cheaper than London.
entry to Castles and museums was at most 400yen usually.
I could usually eat for about 2000 yen (usually with a beer or sake) maybe less seldom more. Breakfast around 650yen Beer is expensive however at about 600 per glass. And there's always the convini.
Hotels ranged from about 5500 a night in business-style hotels to 10000 a night in a syukubou (temple lodging) with 2 meals to 4000 a night in a hostel style guest house. I also stayed in a minshuku which I thought was great value but can't remember the price. fantastic breakfast. The smaller places only do cash and even the hotels wanted the tax in cash even if you used a credit card. (And one rural hotel although they had a credit card machine wanted cash up front)
Post office is the best place to find ATMs to get cash.
Trains. I didn't buy a JR train pass as I was only going to be in Kansai and for the main travel part wouldn't be on JR. Osaka to Himeji I think was about 600yen one way. to Kyoto about 350. In Kyoto I got a two day pass for 2000 I think. Even the longer distance Isobe to Osaka by limited express wasn't too bad.
Not the cheapest holiday I've had but one of the best and if you're learning Japanese you just *have* to go at least once.
I have pictures here with an essay (nihongo de)
http://www.shiawase.co.uk/pres/source/1.html