I love Kim Dare AND Sarah Black...they're both awesome authors. Haven't read Marathon Cowboys yet, though. I'll do so once I have some money again.
Janilee knows this already, Elle, but in my considered opinion the very best in the m/m western romance (the entire m/m romance sub-genre, for that matter) is 'Let It Go' by Mercy Celeste. It is just packed with all kinds of emotion, but I warn you, it is an exhausting read emotionally. Not for the fainthearted at all.