People with cats in New York City enclose their patios for the safety of their pets and call them "catios", this might work for toddlers. But any temporary fix like this might give you a false sense of security. The child should never be left alone in these areas. The door to the child's bedroom should have an adjustable gate, children often learn to climb down from cribs when parents are not looking. http://www.nytimes.com/2010/06/17/garden/17catio.html?n=Top/Reference/Times%20Topics/People/J/Jennifer%20A.%20Kingson?ref=jenniferakingson

Glass panels are a nice option - not sure of the cost though but I'm guessing high...

Thanks for your replies. I like the glass panel idea (we also considered plexiglass, more affordable) but unfortunately it creates a lot of glare with the windows. The catios are interesting--maybe that will work outside, where we have another babyproofing nightmare (a river!).

I see shoji-screen-type door & window treatment (very nice). Could that treatment be made to fit the spaces, without glass or rice paper. Maybe they could be removable like old fashioned window screens so you could take down at a later date.

Yeah, it fits the Asian theme of the house, too, so in some ways it is perfect, but our contractor just pointed out to me that babies can climb the latticework on it. :(

I have a loft that is 13 ft above the floor below and a kitten. It isnot a permanent fix, but I put up bamboo screening like you would put along a fence. It doesn't look "terrible", though obviously, it was inexpensive. I needed something high enough that the kitten wouldn't climb and fall over, so this has worked. It still allows light to filter, and you can see the railing and windows beyond. I see this is 21 months old, so I am a bit late.