We have two windows that are over hot-water baseboard heat. What length curtain should I put on them? I'd like to do two layers - sheers with a heavier curtain on top. I'm concerned about having fabric drape over the heat outlet if I go with long drapes, especially with sheers. Would short curtains look OK? It's for the guest bedroom.

Edited to update: I did some research and found that as long as it's hot-water baseboard it's OK to put furniture or drapery in front. Electric needs to have the curtains 3" in front or 8" above, but for hot water it doesn't get hot enough to be of concern. The water itself is only about 145 degrees. The only issue is that if the curtains cover the unit and are closed all the time you're just heating the area between the curtains and the window.