It looks to me like they are doing just what you said, hanging out. Now that the hives are a little bit larger and they have worker bees to spare for the job, you will commonly see guard bees stationed at the entrances to keep out any intruders. It's also common on summer evenings for foragers to just hang out on the porch when the weather is nice. At its most extreme, this behavior is called bearding, and it results from the adult workers moving outside to help keep the hive cool by removing their body heat from the brood nest. I wouldn't call what your hives are doing "bearding" by any stretch, but remember that bees are cold-blooded and must regulate the temperature of the brood nest for the brood to develop properly, so you may see bees fanning or just hanging out at the entrance to help control the hive's temperature.