I do share your concern about pesticides indoors. Are your cats indoor cats? If so, and you don't have dogs outdoors, you might want to put "ant stakes" around the perimeter exterior of the house. Ants are also said to avoid cinnamon, and I found the truth of this when I tried sprinkling it around a baseboard where they were coming in. I watched them and did indeed observe that they avoided the cinnamon, and instead, moved their trail around it. However, with the high cost of the spice, I don't think either of us would be able to use that as a viable means of deterrence.
We have our exterior sprayed regularly by an exterminator because of the spiders who seem to love living near the water. I'm told that the product they use is completely pet-safe, although we won't let our one indoor-outdoor cat outside for several hours after the spraying. You might contact an exterminator, let him know you have cats, and express your concerns about their safety with pesticide products.