Thanks for all the support and advice! I think I'm going to price out a few different scenarios, and present it to them. I'm hoping that if they know what to expect, and realize that they have a year to save money for it, they will be open to the idea of spending a little extra money. I'm not worried about how they will impact everyone else's vacations. We have all vacationed together before (at least the adults), and are used to them being frugal. It doesn't change our spending habits. On this trip, the only impact might be on the lodging, and if we decide we don't want to stay where they want to stay, there won't be any hard feelings. We aren't planning on touring together everyday anyways.
I'm hoping YES tix will be available. We did get them a couple of years ago during the same time frame, and they are available this summer in August, so hopefully the trend continues! When we used them a couple of years ago, only one adult could attend the class. Is that still the case, or can both parents go to get the better deal on tix?
Thank you JosieMouse for the house rental links! Some of them look pretty promising!