First, you need privacy and darkness and second, you want it to look pretty. If you owned the home I would recommend Flat Roman Blinds. However, the labor can be expensive and it is not likely that you will be able to re-use the blinds due to the variation in window sizes.
If you want to be able to re-use your custom window treatments, I recommend simple flat panels from the top of the window — or ceiling — to the floor.
Make sure to line the panels with blackout lining so the sun does not wake you up early on the weekend. The blackout lining is heavy and will help the panels lay well and protect the fabric from the sun.
For this job, I also purchased ready made sheer linen panels, a double brass rod, and brass rings (my NYC client is waiting for the building super to install the new rod so that she can hang the sheers for daytime light filtering).
Enjoy sleeping in and feel good that you can reuse your beautiful store bought designer bedding and custom window treatment in your next rental apartment or home!