@ BlakelyProperties, making a blanket statement like that is dangerously close to the blanket statement that they DO. Every home is different and the amount of savings seen will vary depending on the original windows, the product and installation used for replacement, along with other factors of the home. I will agree with what I believe is the intent of your post however, in that consumers are wise to think twice about the claims made by some unscrupulous window salesmen. Manufactures and dealers alike have been cracked-down on in recent years for their highly exaggerated energy savings "guarantees", and other such misleading advertising.

Relative humidity is a comparison of vapor density versus saturation vapor density at a particular temperature. Put a bit more simply, dew point is 100% relative humidity or the point where the air - at a certain temperature - is no longer able to hold any more moisture. If the air has reached vapor saturation (100% relative humidity), then the air will release moisture which will show up as condensation on any surface that is at a temperature below the dew point temperature of the air. In order to stop condensation from forming on the surface of a window, you either have to lower the dew point temperature of the air in your home to a level below the dew point temperature of the window surface, or you have to warm up the window surface to a temperature above the dew point temperature of your home, or a combination of both. Lowering the relative humidity of the air in your home may have absolutely no effect on controlling window condensation or it may completely solve your problem depending on "how" you lower the relative humidity and what affect the "how" has on both the moisture level of your air and the temperature of your windows. All this because there are two ways to lower relative humidity  first, you can increase the air temperature in your home or second, you can decrease the moisture content of the air in your home. By increasing the air temperature in your home you will lower the relative humidity but you will not change the dew point  which is based on the amount of water vapor in the air and is not based on the temperature of the air. So, while the RH is lower with higher air temperature, it may not effect condensation on window surfaces at all  unless the rise in air temperature also causes a corresponding rise in window glass temperature to a level above the dew point temperature. But by lowering the amount of water vapor or moisture in your air you will also lower the dew point temperature as well. If you lower the dew point temperature sufficiently to drop it below the temperature of the window glass you should have no more condensation issues. The amount of moisture in the air is typically measured in grams per cubic meter, which is kind of nice for our metric folks but not so nice for our non-metric folks; but the metric version is much easier on the calculator than the English version. However, in the interest of making this stuff easier to understand for all of us non-metric types, I am going to covert back to Fahrenheit rather than use Celsius temperatures in the calculations. Okay  consider your home at 65 degrees F and with a relative humidity reading of 40%. There are 6.25 grams of water in a cubic meter of air in your home in that particular scenario - which then equates to a dew point temperature of 38 degrees F. So at 38 degrees the air will be at 100% relative humidity or at saturation vapor density. If your home hygrometer measures the relative humidity in your home at 60% while the temperature of your home is 70 degrees, you will have a dew point temperature of about 51 degrees  meaning that if the temperature of the window surface is below 51 degrees then you will have condensation on that window surface. Which then begs the question are you seeing surface condensation all over the glass or only at the edges of the glass? Also, where did you place the tmermometer to get those temperatures? Was the thermometer at the edge of the window or at the center of the glass? There will be a difference between edge temperature and center-of-glass temperature which can be significant when dealing with condensation issues. Also, consider that the interior glass temperatures are based on the fact that moving, warmer, indoor air is in contact with the glass at a given time. If the air against the window isn't allowed to circulate, you can have problems as well. Curtains, shades, other obstructions can cause problems by blocking airflow across the glass  airflow that can have a huge effect on the condition of the window relating to condensation. Also, bay and bow windows can be more prone to condensation  again because of the possibility of decreased airflow over the glass. And finally, what can happen to the dew point if you keep your home at 70 degrees and you have a 65% relative humidity? Well, for one thing the dew point has jumped up to 57 degrees and anyone with 65% relative humidity in a home at 70 degrees has way too much moisture in their air and they are in serious need of some sort of ventilation system  or at least several good exhaust fans.

Full disclosure - I am the General Manager for Thermal Windows, Inc. in Oklahoma City, so expect my response to be biased. It seems those who are trying to sway you away from our company are typically not located in the Tulsa market and likely have little experience with our residential window operation. Thermal Windows, Inc. has been in business in Tulsa, employing literally hundreds of Oklahomans, since 1979. The company is certainly one of the largest players in the Tulsa market. Since our start, we have maintained an A+ rating with the Eastern Oklahoma Better Business Bureau, which has several times given us special recognition for Outstanding Customer Service. Angie's List members give us consistently high ratings, and we've received their Super Service Award, a recognition bestowed on only about 5 percent of companies, in each of the last several years since the site's popularity has taken off. As an employee of Thermal Windows, Inc., one of the things I most appreciate about the company is the willingness of top leadership to allow those of us dealing with the public to go over and above in order to satisfy our customers and address their concerns. Estimates are free. Our salespeople are truly consultants. We don't approve of any coercive or high-pressure selling tactics. At most, they will need about 40 minutes to an hour to understand your needs, measure your openings and supply you with a detailed quote. Of course, if you have a lot of questions, they'll stay longer to make certain your questions are answered. (As a side note - Beware of sales representatives who insist on staying in your home for 2 or 3 hours and pressure you to sign a contract or lose out on their best price. Chances are their best price is two to three times the average for a similar product in your market.) So, the real question is this: If you live in Oklahoma, why wouldn't you give the only window manufacturer in the state, which happens to have an excellent record of customer satisfaction, an opportunity to show you what they can do? As far as I'm concerned, if you look at everything from our products, our installation, our service record and our competitive pricing, you won't find better value in windows and doors in Oklahoma than Thermal Windows, Inc. (But again. I'm biased). Check us out for yourself!

Originally I thought Roman shades, but when I read "lightweight, whimsical sheers", I thought of Urban Outfitters, https://www.urbanoutfitters.com/shop/draped-shade-curtain?category=window-curtains-panels&color=004 and because all of their curtains are on the more whimsical side, I think you could pick any to use with a tension rod, because you don't have room for proper curtain rods, https://www.urbanoutfitters.com/window-curtains-panels