Talmud Bavli (Nedarim p. 20b) quotes the majority of rabbis (who disagree with the fringe view of Yohanan Ben Dahabai) who are lenient by stating that "all that man desires to do with his wife he may" (provided she agrees[1]).
2 p. 244) commentary to the Torah points out that the kohen personality is to be extra-scrupulous with oral-vulvar stimulation of his wife when producing offspring, as per Rabbi Yochanan's ben Dhabai's warning that it may cause a physical blemish were his wife to conceive; as a kohen is bounded by the Torah rules of kohanic disqualifications, and may be disqualified from specific Bet HaMikdash services if he has a physical blemish.
240) takes a stringent view of oral-vulvar stimulation by stating that the transgressor violates the spirit of the Torah verses of והצנע לכת ("Thou shalt walk humbly" -Micah 6:8) and בעבור תהיה יראתו על פניכם לבלתי תחטאו ("So that fear (of God) should be on your faces so that you should not sin" -Exodus 9:16) and of בל תשקצו את נפשותיכם ("Thou should not make your soul despicable" -Leviticus 20:25).
25) adopt a more lenient view on oral-vulvar stimulation, as does Rabbi Yoel Sirkus (the "Bach") who permits it in accordance with halacha, but nonetheless discourages its practice.
A similar point of view is written by Rabbi Shlomo Blumenkrantz[4] who states that the Remah, Chelkath Mechokek and the Aruch HaShulchan all agree that one may do with his wife as one desires – including oral-vulvar stimulation – as this is not punishable according to bare-basic halacha.