I'm glad this was brought up. Rates are a multi-layered subject. The first layer is the external stuff- location, marketing, and how busy you choose to be. The second is more personal-looks, services, and the other things. What works for one lady even in a particular area doesn't necessarily work for another in the same area marketing herself in a similar way.
My marketing strategy is completely bonkers from most ladies in my area. There are a few others like me, and it's all because we have civvie jobs. I can afford to wait on the guys who want to spend the time with me that makes me comfortable. I'm not any more expensive per se, but it's more about the quality of the experience and not the quantity for me. Right now, if I didn't have a date all week I could care less. But if I didn't work, I would most definitely do shorter dates and my rates would be most like the other ladies.
When I get to London, it's going to be a different issue. The goal will be to see as many guys as humanely possible, while still remaining sane, healthy, and able to be polite. This is where I'm having to take a look at things. The area I'll be in and my marketing will have a big effect on my success. I'm considering my maximum and my minimum. Whether or not I should 'tour' different areas on different days once I get my footing. I'm having to consider all my options should my Plan A falls through. I will need to be as flexible as a noodle. A cooked one anyway.
Always take into consideration your own circumstances and go from there. If what you're doing doesn't work, as in you're not meeting a financial goal, firstly look at yourself and what you're willing to change (or not), then change your rates accordingly. If at 120 an hour you find yourself mindbogglingly busy, it may be time to raise your rates and step up your marketing.