Those are all personal preference issues.

All will work and give you roughly the same amount of glass is similarly optioned out.

A single entry with sidelites is likely to be a bit more secure and air tight but if you like the double door look, a well installed one will do just fine.

Any opinions on putting a trellis or other feature over the door or along the garage to add some curb appeal?

The windows on the right side of the front door are for the garage. We are thinking of taking these out and replacing with one smaller horizontal sliding window with privacy glass. Thanks for any opinions.

Did you mean vertical sliding window?

You have some fascia board rot above the garage entry door as well.

Can't really offer any real feedback on the trellis idea. It will provide some shade but I have seen enough rotted trellis where they tie into structure and I prefer to have some rain protection as well.

California contemporary homes are tough though because you really have to be aware of the aesthetics and what works with them.

Here is a picture of what we are thinking of doing?

However, I would love to be able to have a window that would open for air into the house from the front.

Should we use a casement or slider or an awning at the bottom or top?

What about privacy glass? Should we use something other than normal clear glass?

I think your are on the right track going to single door and adding a window. I think a trellis would look good depending on design of course. I am not a fan of obscured(maybe reeded or hammered?) glass but you may be limited on choices depending on the window company, but you can always have your own custom glazing installed. You could maybe do a cottage/oriel style double-hung window with either sash larger than the other.May replace the front garage door with something to jazz up the front of the house? Maybe a couple of dormers in front as well or maybe some trusses on the garage that overhang the sidewalk.I can't stop staring at the skylight either,it's like a big pimple but the trusses wold cover that.