interaction with the girl and if you know how to sweet talk it helps you with appts down the road, plus its hows her you're into her.

Unless her hourly rate is already quite low, but that is very rare.

 
I like the multi-hour because you can relax and not worry about the clock as much, but most gals do discount the second hour and then even more for longer sessions.

Would it be inappropriate or a bad idea to ask the booker if there was a lower $/hr rate if I were to book a multi hr visit?

All "hours" are the same.  It makes no difference to her or the booker if you spend the second hour with her, or the next guy after you takes that hour.  As Silky says, If you want to improve the connection, booking two hours will give you a little more "chat" time between pops to get to know each other.  I think one reason I have a lot of success getting outside dates is because I only book one hour with a brand new girl.  The repeats are all two hours.  The extra time I allows some social time.  It gives them a little time to size me up (no pun intended) too, if THEY'RE the ones interested in outside dating.  THAT'S where you make the connection, not while fucking.  Fucking is just theatre for them and doesn't require any thinking on their part.  You'd be surprised how many Kgirls that fuck 6-7 guys a day are lonely in real life and looking for someone comfortable to hang with when they're off, but they want to be the ones to choose, and will say no if asked outright for a date by a customer.  Letting them get to know you helps them choose wisely.  

As others have said, multi-hour sessions are better in that you (both of you) can relax more and chat and not worry about time so much..  And, if you're up to the task, you can go more rounds and both of you can explore more positions, etc.

The last time I booked a 2 hour session with a K-girl, it was off the charts for me.  She was my ATF and I had already seen her a handful of times.   Since you're talking about your ATF, I would think you'll have a fantastic time.

A K-girl's hourly is still are a deal even with $10 to $30 increases for some, so I don't see doubling their hourly as a dealbreaker.  But, that's just me.

What others said are right but I can get what I want with 1hr session so I am not inclined to go for multiple hours. I am not interested in OTC dates or getting to know them so I am better off with separate 1hr sessions and I only booked multi hr when I could not get enough of her in 1hr. This was the case for a very few girls and I wouldn't know if the sex got better because I already had a great time even with 1hr. I never expected or asked for discount with multi hr sessions.
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Try it with your ATF at least once. She likes to talk and may be you will have an awesome time.

I do 2hr sessions cuz I can nut 4-5 times in 2hrs.
So I seek kgirls that are go go go in their reviews.  PSE types.
I use blue pill for these session.  Only need like 12.5mg.

Here in Vegas: 1hr = 3, 2hrs = 5.  See that pricing in LA sometimes also.