I don't feel guilty about killing insects, there's more of them then all of humans combined. When it comes down to ants, I lean more to the thinking that they've invaded my domain and I'll do anything to rid them from the house. They would do the same to another colony or even other insects that have stumbled upon their colony. One of the more annoying type of ants is the sugar ant. Their size is very tiny and they tend to be quite hardy. We've used ant trays that have a small amount of pesticide inside them.
I've used raid on wasps and the other more aggresive type of wasps (yellow jackets and the like). I do leave honey bees alone as they serve much needed role in nature but wasps, no. They're on my list of insects to wage war on. With spiders I sometimes don't have any issues with. Take the wolf spider for instance, I usually let them be as they feast on cockroaches. Which down here is a very good thing as Florida is full of them. But I will try to relocate a wolf spider as best as I can. Plus they don't bite you, well not if you tick em off.