Ive written a few patterns and I usually add at least three different size options just because I know that some people hate doing the math for fabric requirements, etc. Making the extra (or less) blocks to change the size is usually the problem for people. It's the fabric requirements, especially if they are using yardage and not making it scrappy. I made the decision to do this after teaching one of my patterns at a local quilt shop. I received multiple calls from the shop and students asking about making size adjustments and since it really isn't too difficult for me, I decided to go ahead and do it. I honestly believe it has helped sell my patterns and classes.
I teach a series of beginner-type classes and in the lessons, I include a lesson on how to figure yardage. I have had some students who say they don't care and will just buy what is called for in the pattern, but I know others have really appreciated the information. As a matter of fact, a "repeat" student recently told me that she learned that information in a class over three years ago and has just now started using it. She said she needed time to gain enough confidence to do it on her own and now she can make quilts the size she wants without just adding or removing borders. I was so pleased!
Someone mentioned that they are bothered by a pattern advertising "3 Bonus Quilts" when in reality it is just differet sizes. The only time I state that you get a "bonus quilt pattern" is when the layout is different or when the actual block can be made differently, thus creating a new quilt. I agree, a size change is NOT a new quilt.