I added tint to my CRX last winter. 35% all around for $160. It seems to help keep the car cooler, and it does enhance the look imo. If your A/C is broken though, tint might not be the best idea right now. Typically there's a 3 to 5 day waiting period on new tint before you can open the windows, and with this heat wave that could be hell.
I used to tint windows for a living. And I do it for friends and family now. It does make a big difference. I've tried several different types of tint on all of my past cars, and it was always noticeable. I would recommend a tint that is colored with metal rather than ink. It will last forever, never change color, and reject a lot more of the heat.
The film I use is from Sun-Gard. I have the Endurance 20% on my car. I've worked with Solar-Guard as well, and I'd recommend their Titanium line. I've never used 3M or Lumar, although they are supposed to be good as well.
Right after I bought my car (13+ years ago) I had the windows tinted with 35% 3M metallic tint. It still looks great after all that time. It's also kept my interior from fading. I live practically in the Gulf of Mexico so sun, heat, and humidity are an everyday experience. The tint helps, when I park I use one of those windshield shades, and raise the sunroof (at work only, we have security) to keep interior temps from soaring. Finally I got my AC professionally replaced a few years ago with a R134a conversion. It wasn't cheap but it's some of the best money I ever spent......
Also, I am very aware of where the sun is when I park. If I cannot find shade, I park with the back of the car facing the sun. Then I take my four Magic Shade Collapsible sunshades and put them to the windows. Two for the front window, and two for the back.
The back ones I put up by wedging one at the top between the hatch hinges and the other at the bottom of the trunk with something back there holding it vertical. When I close the hatch, the bottom shade holds the top shade flat against the glass. I leave them in place when I am driving and it cuts down on the heat tremendously.
I also leave the windows cracked about an inch as well as the sunroof when I park.