Few doubt that suffixes or prefixes, affixes in general, are a useful tool in a conlanger toolbox, but how precise should they be? In this respect I tend to think: the broader the meaning the better. To me it's actually a lot of fun to be able to have an arrange of suffixes with broad meanings and play around with the possibilities that can be unlocked with them.
One example I am specially fond of is Esperanto's -aro and -ujo suffixes. The first one roughly means "a group, heap, collection, set, herd" and is mainly used of groups of things that form a sort of collection, such as words in a dictionary, or the human-kind in general, while the other has an approximate meaning of "jug, box, container, vessel" and it's used mainly to mean countries (containing people), or more even interestingly trees from their natural fruits. So, for example, you have vortaro to mean "dictionary, a collection of all the words", homaro "humanity as a whole", and on the other side you have Hispanujo "Spain, the country", and pomujo "an apple-tree". This brings many possibilities worth exploring. You could talk of your library as either libraro or even librujo, but they would have subtle differences.
In the case of libraro it means the collection of books that constitutes your library, i.e. your books as a whole. The second case implies the container wherein those books are set, i.e. your shelves as a whole, the whole furniture. Therefore you would have a knowledge of your libraro, but you would want to move your librujo around your bedroom. This is interesting because with only one little suffix you get two different words connected while, at the same time, subtly different in their sense.
In my languages I have tried to keep this in mind and use it, specially in Unnai. In that language I have some suffixes that have very open and broad meanings that depending on the noun or adjective they are attached shift and mean new things. There are, of course, other interesting suffixes in Esperanto, one I particular like is -ingo, a suffix Esperanto uses too mundanely and logically but that I think used in other languages or conlangs has many possibilities. It basically means "an object in which the noun to which it's attached is introduced". Let's see a practical example: fingro "finger", gives fingringo "thimble". As for ideas for conlangs one could stretch it a lot more, it could just mean "something in which other something is introduced", you could have soul + this suffix meaning "body", a poetic version, of course, or how about feelings + suffix meaning "heart"? Well as you see it has a vast number of possible ways to go.
So, to sum up, keep your suffixes open and wide you never know when you could need a stretch in meaning.