reply to Fronkman
Re: windows windows windows We had installed Infinity Windows by Marvin, and have been very happy with them.
They are a fiberglass based material, so they are much sturdier than vinyl, and have nearly the same coefficient of expansion as the glass. Not sure if this is the same as the "composite" material you are referencing.
There is also an optional wood veneer for the interior surface which can be stained like regular wood.
I don't know if they offer an external grill option, so that may be a deal breaker for you. However, if you are trying to make them look like individual panes of glass, I think they have an interior grill option that accomplishes that.
We have a mix of double hung, fixed, and casement. We have white/white, and some with interior wood veneer. We do not have grills.
Our average cost was about $1100 per window, installed (16 windows).
At least take a look and get a quote. It looks like there are 4 dealers in the St. Louis area that handle Marvin windows.