Main Anime characters:

Genjo Sanzo:  The monk of the group.  Don't let the religious parophanaliea fool you.  He smokes, drinks, gambles, cusses like a sailor and does who knows what else.  He's emotionally secretive, cold as ice on the outside, violotile, abusive to friend and foe and absolutely drop dead georgeous. The blonde, violet eyed one out of our group of mis- matched hero's.

Sha Gojyo: the ladies man.  the tall, lean, sexy one.  His mother was a youkai(a demon) and his father a human.  When his father abandoned his mother, she eventually grew to hate and resent Gojyo as a living reminder of her lost love.  She tried to murder him when he was a child and his step-brother stepped in and saved him.  He's been holding back that guilt/horror/mother-hates-me thing for a long time.

San Goku; the boy, who's not a boy.  he's a youkai actually.  He's like 500 years old, but due to some fiddling from the celetials from something done way back when, he's got this perpetual kid-like mentality.  He's cheerful and outgoing, but a fierce fighter.

Cho Hakkai:  He used to be human.  But when a human kills 10,000 youkai, so the legend says, he becomes a youkai himself.  Hakkai went on a killing spree when his sister/lover was taken and subsequently killed herself because of it, by Youkai.    He's the level headed, cheerful one of the bunch.  The one who always has something optimistic to say, the moderator.
 
Story synopsis:
After 500 years someone bad is trying to ressurrect a big, bad youkai that
will wreck havok on the world.  the powers that be send Sanzo and his ragtag
crew out to the west to stop this event from happening.

Slash potentials:
Okay, my personal favorite is:

 Gojyo X Sanzo.  i think Sanzo's too closed off emotionally to initiate any relationship by himself and Gojyo is just forward enough to pull it off.  i see it as a love hate thing.  I see it bordering on violence, because Sanzo can't admit to wanting anyone or needing anyone.  Even in the anime and manga the  sexual or violent tension between the two of them is thick enough to cut with a knife.

Gojyo X Hakkai;  there's a lot of actual basis for this one.  Gojyo saved Hakkai from killing himself, back before they had met Sanzo and Goku.  He nursed him back to health and has a really steady friendship with him.