Living near a highway in SoCal with no standard windows - how to install A/C?
As mentioned in another answer, casement window air conditioners are available.  

The portable units work okay.  Obviously they eat some floor space.  You may have to empty the condensate that collects.  You have to run a dryer type hose to exhaust hot air.  The units usually come with a mounting bracket that go in a window, but somehow these are always useless plastic junk.  However it's very easy to make a plywood window bracket for the hose.  It's not that hard to install a permanent dryer vent if you'll use the same unit in the same window every year.  

You can buy air conditioners that are made to install in a permanent wall penetration, search for "through-wall air conditioner" - they usually have a sheet metal box that stays in place year round.  There is obviously some carpentry involved but it's not too difficult.  If you can place them below a window, usually you don't have to install a header over the opening.  If you don't want to DIY it, it's not something for a handyman, but an easy job for a carpenter.  

I think the ductless will be your best option - they are a lot more money, but popular for good reasons and although definitely advanced DIY, DIY-able.  


Flexible options for location of indoor units  
Efficient electric heat for moderate climates 
Quiet 
No annual installation / removal 
No cords 
No compromise of security (break ins)  
No drafts around window units 
Adds value to home