"Ogon" is used occasionally in this meaning, sometimes in a playful context. But I would call it an euphemism rather than a word for penis, and I can't recall hearing it too often in other context than a fixed phrase or a proverb "czym kot starszy tym ogon ma prężniejszy" (literally: the older the cat, the stiffer is its tail). It seems to me that "chwost" (an archaic word for the tail) could also have been used - but I can't recall if I heard it in an actual rural dialect, or only as a stylisation in literature.
A much more common euphemism is "ptak" ('a bird') or its diminuitive. It's also used in a fixed phrase "klatka wielka, ptaszek mały" which sarcastically refers to a man with a big chest ("klatka" = "cage" or "chest"). However if I do not want to use the word "penis" (which sounds medical and bookish), and don't want to sound rude or childish either, I would probably use this one.
No associations with tails in Russian, that's for sure (not that I heard of at least). Aside from phonetic substitutes like "хер" (a historical name of the Cyrillic letter "х") and "хрен" (horseradish), extended pompous euphemisms ("man's dignity", "childbearing organ" etc.), variations of child words, more or less formal terms ("член" - "member", and, obviously, "пенис") and almost entirely random occasionalisms like, for example, "стручок" ("silique", "pea pod") or "отросток" ("appendage", "sprout"), I can only think about "конец" ("tip"; "end").