Earlier this year I discovered Spa World in Osaka (
http://www.spaworld.co.jp/), and I have just recently went back a second time (staying at the Spa World hotel again, that makes it very easy to go down to the facility in the morning, then go out for 2/3s of the day, and return back in the later afternoon for some nice relaxation). Living in Hawaii, Japan being just a quick 6-7 hour flight away, it's really easy for me to go over for a few days of relaxation and rejuvenation at the onsen -- that really helps given my very stressful work.
I have been trying to find some other similar big onsen facilities in Japan, but have come up short on my searches. The ''super onsen'' or ''super sento'' in Tokyo are all (at least, the ones I've went to) just 1/4th size of Spa World, at best.
Basically, what I am looking for is:
* a large facility (2000+ guests capacity at a time) with many various large baths (indoor and outdoor), saunas, etc. - where there is enough variety to go back a few times and stay in for some two+ hours at a time
* preferably conveniently located (close to train or at least metro station) in a fairly large city, with things to see and do there during the day (with easy access to and fro)
* preferably with a directly attached/part of it hotel (so can stay there, and when one goes down to enjoy the facility, no need to put on street clothes, can just go using the provided clothing)
Is there anything else like this (similar to Spa World) in Japan?
In Korea, I've found Hur Shim Chung in Busan (
http://www.hotelnongshim.com/eng/hurshimchung/hur_intro.asp), that seems quite similar to Spa World in Osaka - only (it seems) even bigger (and with a surely much bigger attached hotel). (Actually, the day after I found it, I changed my next summer return flights from EU to Hawaii to add in a brief Busan stopover, to relax a bit on the way back from my working vacation.)
But, I've come up short of anything else like this in Japan.
In Tokyo it seems for sure there is nothing.
There is the Nagashima Spa Land (
http://www.nagashima-onsen.co.jp/resort/download.html/) in Nagoya (I mean the onsen part, not the theme part part that I am not intersted in), but it seems to be a bit inconveniently located (a rather lengthy bus ride away from the closest train station), and also doesn't appear to be really as big as Spa World (on their site, I can't really find a map/outline of the onsen facility, just some very general words on it only claiming that it's big)... though it's a lot more outside, so still I guess worth a visit (?).
Then in Noboribetsu, Hokkaido there is Dai-Ichi Takimotokan, but it also seems to be a rather small facility really (
http://www.takimotokan.co.jp/english/facility/spa.html - seems less than 1/5th the size of Spa World in Osaka).
So, my question is, what am I missing? Any suggestions for something similar to Spa World in Japan (or Korea, other than Hur Shim Chung in Busan - the advantage of Korea is of course notably lower cost than Japan), where I can go and stay for some two or three nights to relax, enjoy the onsen (that is hopefully large enough with enough variety to keep one there for a good few hours each day for 2 or 3 days), while also having things to see and do during the daytime outside?