Well, many fine films have erotic moments or undercurrents without being mainly sexual, but it's harder to think of great tasteful erotic films with plot. So here's a variety of suugestions; 

 The Mother and the Whore (threesome, and sex is a theme, but very talky, though); Goto Isle of Love (more quirky than erotic- Borowczyk's later films, eg Immoral Tales, are more openly sexual); In the Mood for Love (certainly tasteful, only subtly erotic); Claire's Knee, My Night with Maud, A Summer's Tale (these and some other Rohmer films are full of dialogue but have an underlying sexuality); One Deadly Summer (Isabelle Adjani is sexy in this, but it turns more serious than first impressions suggest); Belle Epoque (light-hearted agreeable Spanish film in which a young man staying with an ageing artist enjoys the hospitality of his 4 pretty daughters); In the Realm of the Senses (Oshima's controversial film- art or porn?); Les Valseuses, aka Going Places; has a threesome and is enjoyable though it's not specifically a sex film; Betty Blue has a famous opening scene; Tinto Brass directed many soft porn films with some pretensions to tastefulness;, Les Amants caused a stir back in 58; Conspirators of Pleasure (Svankmajer) is a bizarre mix of live action and stop-motion animation that hints at all sorts of "perversities". 

 I'm sorry, i don't think i've done very well- much of this is quite tame. No doubt there are many i've missed, which will occur to others, or to me after further thought. As i said, many of the scenes that come to mind as sexy are not in specifically erotic films. 