Be careful with window tints, or window films. Adding these items can void factory warranties and leave you liable if they contribute to a glass failure.
The tough part here, is that you don't know for sure if there is even a problem that needs solving. I can appreciate your concern, however. But hopefully, the architect/designer took these concerns into consideration when he/she designed the building and used glass that cuts down solar heat gain.
If not, any one of the solutions will help, even the metal blinds.
Most window treatment stores/suppliers have larger samples you can bring home and get an idea of how they will look installed. From there, just pick the one you like best.

I just helped a friend with the window treatments for her loft [she is doing my website].

We stretched wire cable across the tops of the windows as the 'rod'. Then we took panels of muslin - that loosly hung from clips from the cable [about 8 clips per panel so that there was a droop at the top between each clip]. You can also use grommets and just 'string' the panels on the cable.

To make the panels appear more high-tech/industrial we stamped across the panels about 5-6 feet from the floor with a graphic design. The natural color of the panels with the large black graphics - Looks great! Very inexpensive and the muslin blocks enough light that the room not only feels cool but looks softened a bit and cool.