A new construction window does not always mean more glass. It depends on window type and size and manufacturer. When we replaced our old leaky Aluminum windows with AL clad, wood interior windows (Marvin Ultimate), we ended up losing about 6+ inches of glass. The old aluminum had skinny sash while the new ones have large wood pieces inside. The large wood pieces did not affect the views as we feared but they certainly did not yield more glass. There are several reasons to stay with replacement even when changing siding and trim. We lived through this in our previous house. When trim around the windows is expensive to replace and already matches the house trim. WHen original frame is sound and we are not changing window size. When replacement window is sufficiently better than old window. When project cost of new construction is way higher than replacement windows. WE ended up using replacement windows for our previous home. For our current house, the trim was bad and needed replacement anyway, the framing surrounding the windows had visible water damage and there is no replacement for those poor quality Aluminum windows. The end result was new construction windows.

John, Some pictures will help out us by letting us see what you see. As a general rule, if you are setting a pocket/insert style window...you will have to cut through or removing the flange if we are talking about a vinyl window.

Another option which we don’t want is a picture window which does not open & we want something that has the ability to open. With casements, be mindful of the prevailing wind direction. You don't want the cranked out window to block the prevailing wind. If the windows are on the side of the house that catches prevailing wind, be mindful of which direction the window cranks out. Also, if the house is oriented so that the windows catch prevailing wind, it doesn't do much good for the middle window in a 3 window bank to be operational. The middle window can be fixed glass.

I think your humidity is too high and if you have hydronic hot water radiators for heat not enough air circulation. Wash your windows and the wood immediately around the glass with a tri sodium phosphate solution, a half cup or so in a half bucket of hot water, buy the tsp powder at a paint or hardware store, squeegee the glass and wipe the wood dry with a towel, the slight remaining tsp prevents mildew, mold growth. Tsp is the active ingredient in some commercially available mold killer/inhibitors. Wear rubber gloves to prevent skin irritation. t is great to remove grease, dirt, mildew prior to repainting kitchen and bathroom walls. I would think this might save you the expense of replacing windows and if your humidity level is not reduced you might still have condensation on the window glass.