Jared,
From your pictures, it appears all the plants need to be planted in larger pots. As big as they are, no doubt, the roots have pretty well taken up the 4" pots. Without more soil, the water will just run through and won't stay with the plant.
After re-potting the peace lily will need to be watered every day regardless. The pothos and the palm should be watered when the soil is almost dry to the touch. The aloe and the snake plant are succulents and store water in their leaves, so are not fussy. Both of these will multiply in their pots and will need to be potted up more frequently.
Jim mentioned the medicinal value of the aloe, but also note that, the balm of the aloe is good for stings, cuts and scrapes. It helps in the healing process and cuts down on scarring of the skin. I share these with all my friends for that.
As was mentioned above, most any plants can help with the air quality, beyond that I am out of my realm.
