Houston Zoo has a sifaka exhibit that has a number of climbing opportunities, but the best that I've seen is perhaps found at Sacramento Zoo. Saint Louis, Maryland, Bronx and Philadelphia all have exhibits for Coquerel's sifakas that are average at best, with Maryland and Bronx limited to all-indoor habitats. Omaha now has a supposedly decent sifaka enclosure after the 2010 opening of "Expedition Madagascar", but it is a pity that these primates are not widely spread in AZA-accredited collections.
I just want to add that Maryland Zoo has outdoor access as well. But it's only given to the two male juveniles. The parents and new baby are still in the indoor exhibit.
