I am trying to get a grasp on the locative here, and I’m wondering how to distinguish between, say, the -ovi and -i endings for muž-paradigm masculine animate nouns (and, for that matter, other locative categories where multiple options are given).
Apologies in advance if this has already been extensively discussed somewhere — I did attempt a search, but my first couple of attempts were either too broad or too narrow, so I figured I might as well ask...
For dative and lokative there are indeed two possibilities and the right choice is an advanced topic. I suggest trying to get some feel for that from reading or listening natives first. Sometimes even the natives might hesitate which one is better.
There is an article about it here, but in Czech, of course http://prirucka.ujc.cas.cz/?id=224 You can try an online translator, but they are often rubbish.
Namely for the muž-paradigm -i is more common for common words. For people's names you use -ovi if the name stands separately zavolej Tomášovi, Ondřejovi, napiš Hanušovi. If there are multiple words and names in a single expression you use -ovi only for the last one o spisovateli Ondřeji Hanušovi / about writer Ondřej Hanuš.