I've been to Korea many times on business and was frequently taken to the "kissing bars" or room salons you mention- usually at the conclusion of our business on the last day.

While its fairly easy for foreigners to meet providers in all the usual places, such as the major Seoul hotels, if you want to go to the places you mentioned, I'd suggest you ask one of your Korean business colleagues because it's difficult for westerners to find them.

It's very acceptable in their culture for the men, including the married men, to go out at night "on business" and take clients to these sort of places.  In fact, they're usually quite happy to accommodate your request, or they may even bring the subject up if they think you're OK with it.

It's difficult for foreigners to find the sort of places you're talking about on their own, but it's very common for them to be taken their as the guest of a Korean host.  Every time I went to one of these places, the Korean guys made the arrangements for me, and usually even did the negotiation with the mamasan.  Sometimes I paid them that evening, other times they'd handle it and I'd reimburse them the next morning in the office.

Not all the girls that work in these places will go back to your hotel.  This is one of the reasons why there's always a lot of negotiating back and forth.  But the ones that will go with you spend the entire night, not just an hour.  You should always pay for their cab fare home in the morning, and I always offered to buy them breakfast or room service if they wanted something to eat.  A nice tip is always greatly appreciated.

These aren't massage parlor girls, so acting like a gentleman will be rewarded.  Unlike in Japan, they are always in their 20's (the oldest I was ever with was 27) and many are college students.  You'll also find most are quite attractive, though I got the short straw on a couple occasions.  It usually depended on whether I was the highest ranking guy on the trip, or just carrying the bags for the president.  The Koreans are very conscious of position and social status in all aspects of life, and getting laid is no exception.

If the girl likes you she may give you her number so that you can call her directly next time.  But use your head, just like here.  You can search this board (maybe a year back) for my post about my very own Korean stalker and the problems she cause me.

I don't know about the kissing rooms.
But I would suggest to try www.massagekorea.webs.com
I used them last time I visited, and they were great, and reasonably priced.
Tell B what you are looking for and he will hook you up.