The Hebrew word that the NWT translation is translating as please (na) has a range of meanings which generally are used as an expression to exhort one to do something, such as please, now, I beg, may you, etc. It is more of an emphatic modifier. When translating a passage, translators use the context of the sentence, syntax, and grammar to select the best possible interpretation of a word. Since in Genesis 13:14 the Lord is commanding Abraham to do something, they translated it as Now instead of Please. If you check out the same passage in the Greek Septuagint translation, the word please is not included. However, the word look, the verb immediately after the Hebrew word na (please or now) is an imperative verb, in other words, the Jews understood it to be a command, not a request. So it seems the vast majority of Bible translations are probably on the right track either not translating it, or translating it as now or something along those lines. Keep in mind that the NWT stands apart from the vast majority of translations in the world, primarily because much of their word selection is driven by the Watchtower Society over and above what is dictated by the rules of Hebrew and Greek grammar and syntax. It cannot be rightly called a translation. It is much more of a commentary.
