Lampert Dias Architects, My wife originally wanted french doors when I mentioned replacing the window with a door and she mentioned it again last night. Where we live it gets pretty cold and the last I checked French doors and energy efficiency do not play nice together. We might have to give that option some serious thought because I agree it will look great.

We have French doors in the Northeast, which get pretty cold, and have had no issues with losing heat. Since you have a door on the far right of the the house, I think French doors are more in keeping with the style of your house than sliders.

I also like french doors as you get to open to the full width of the door space. As you have two other doors visible in the photo you would need to decide which style to go with. Personally I prefer the 9 pane style, but have this in full length glass (so anything between a 10 to 18 panes per door), though given your windows are one pane glass you could have french doors with plain full length glass to be of a similar style. I'd also look at toughened glass that has insulating properties.

If this is the front of your home, I would not add a slider there without creating privacy with a site wall or otherwise creating a screen. I agree a french door would be superior and since I have both I must say that one is not superior to the other from a thermal point of view - in fact, french doors typically have less glass area due to frame requirements so don't have the same leakages issues.

A taller window - with sill at seat height - around 18" would accomplish the increase in light and air without sacrificing security and privacy. .

Thanks for all the input, you all truly helped in making this decision easier. We're going to replace it with the same style window.

This is a little embarrassing but we decided to go with the french doors. We picked out the door we wanted and was about to order it when a critical question was asked. "What are you going to do about the baseboard heater?" This lead us down a path of radiant floor heating, which would have to be electric because the house is on a slab. Then we had to confirm the floors we already ordered and paid for is compatible with electric radiant heat.
With the family room being roughly 400sq ft the cost of installing the radiant heat and all the additional work needed just to accommodate the door put the brakes on the door.

It's not all wasted, with the money saved just from installing the window vs a door we're going to replace all the windows to the front of the house instead of just that one.