Latin dictionaries and glossaries don’t typically seem to provide any help when declining names and places used in Latin authors. Is there a single source for such information…?
Salve pmda!
While looking for LPC-resources I stumbled upon something which might fit your bill, at least if you do not need information about obscure places and persons:
The New dictionary of the Latin and English languages; with an appendix of Latin geographical, historical, and mythological proper names (Archive.org, PDF, 21 MB) is a Latin-English/English-Latin dictionary which also contains - as the title says - an appendix of place names and names of persons (only Latin-English not vice versa). It is 22 pages long and gives gender and genitive for the entries. The appendix is a little bit hidden. It begins at p. 177 of the Latin-English part.
The English-Latin dictionary part is not bad either (from a neo-latin point of view). I always wanted to know how to translate “adventurer” (e.g. in an RPG-context) into Latin: periclitator.
Valeas beneque tibi sit.
Carolus Raeticus