Is Nagano worth more than a day trip

Hey guys, hoping I can get some opinions.
Im set to head to Japan on the 2nd leg of my RTW trip in mid to late May - I can't wait.
There are 3 cities I want to visit - Tokyo , Nagano and Kyoto.
The first two are obvious, Nagano - abit more obscure. I am an Olympic nut, so would love to visit as many past host cities that I can. I realise Sapporo is one aswell, but Nagano is far more relevant for me.

As it stands, I have accom booked in Tokyo for 6 nights, at the start of my trip.
The question is, for someone whose only real reason for visiting Nagano is its Olympic history, is it worth staying more than a day - or would be it be better treated as a day trip. (I will be getting a JR pass).
If it's mroe than a day, I will be there for a few days, and Kyoto for a few days - then sadly, will have to move on to my next destination.
The other alternative would be to include it in the Tokyo portion of my journey and then spend more time down in Kyoto - perhaps taking day trips to a place or two I wouldnt have planned to visit, such as the near by Osaka or even Hiroshima?

Obviously I am ultimately the one who decides, but id be keen on some opinions on my options.

Cheers guys, advance thanks for any help.

mat

The city of Nagano has little to see besides wonderful Zenkoji, but there lots of interesting places around the prefecture of Nagano that could easily keep you busy for an entire week:
http://www.japan-guide.com/list/e1216.html

I agree fully with Uji. The Kiso area of Nagano-ken is wonderful, and I'd recommend Narai for a return-to-the-Edo-period experience. The city of Matsumoto is also well worth a visit - more-so than Nagano city itself.