Quite a few people like the idea of a glassed in room for additional living space to replace their deck.  With operable screened windows it seems a sun room would have the best warm weather and cool weather use, therefore extending the usability even beyond a screened room.  Some people call this type of room a “three season room” and some call it a sun room, but whatever you call it, it can add a great deal of usability to your back yard space.   As with many remodeling projects the details of design and construction mean a lot.  The amount of sun and shade on your site need to be evaluated.  For example if multiple windows face south or southwest with little shade the room will be exceptionally hot in July and August in Kansas City.  There are many ways to mitigate this in design and construction, but if not considered it can drastically reduce the utility of such a room.  In addition a typical all glass sun room with 80-90% glazing surface can be very cold when facing north or northeast in the cooler months because it doesn’t get the amount of sun it needs to warm the room in cooler temperatures.  Multiple design choices can control the above issues and make the room more comfortable and usable, but the goals of the end-user must be considered in detail since different people have  different ideas on how they plan to use their room.  If you are considering a sun room, three season room, or even a room addition, try to discuss your normal plan for usage.  Will you use it 12 months of the year, or only 6?  The difference between these plans calls for some detailed design and construction changes.   In this type of room, one design does not work for everyone, and your long term satisfaction will hinge on the thoroughness of the design and construction process.