drunk / drunken
As an adjective, the form drunk is used after a verb while the form drunken is now used only in front of a noun. Thus you should say They were drunk last night and A drunken waiter at the restaurant ruined our evening... Drunk and drunken are sometimes used to make a legal distinction, whereby a drunk driver is a driver whose alcohol level exceeds the legal limit, and a drunken driver is a driver who is inebriated.
sensual / sensuous
Both of these adjectives mean “relating to or gratifying the senses.” Sensuous can refer to any of the senses but usually applies to those involved in aesthetic enjoyment, as of art or music: the sensuous imagery of a poem. Sensual more often applies to the physical senses or appetites, particularly those associated with sexual pleasure. A sensualist is someone who is excessively devoted to eating, drinking, and sexual indulgence.
unexceptionable / unexceptional
Unexceptionable is derived from the word exception in its sense “objection,” as in the idiom take exception. Thus unexceptionable means “not open to any objection,” as in A judge’s ethical standards should be unexceptionable. Unexceptional, in contrast, is related to the common sense of exception (“an unusual case”) and generally means “not exceptional, not varying from the usual,” as in Some judges’ ethical standards have unfortunately been unexceptional.