Rathan - if you're Referring to Ghost as in the "undead apparition", then I'm going to have to say no, I've had real problems DMing for them in the past every time I've allowed them. I dislike Incorporeal PC's.
Shayuri/Fenris - twenty levels in a base class at Epic just seems rather boggling to me.. If you're going to invest that much into the class, why not take it Epic? (Mechanically for the bonus feats, Thematically for the feeling of "I'm a <insert class here>!")
As far as the particulars..
Rogue - If you're going for a sneak attack character and you like a lot of the Rogue special abilities (Imp. Evasion, Crippling Strike, Defensive Roll, etc) then lots of levels in rogue are definitely worth it. Especially if you're taking the Epic feats that have them as Requirements (Epic Dodge, Lingering Damage, Self Concealment, Sneak Attack of Opportunity). But even then, if you're not taking it to Epic there's no reason to take it past 19(When you get your last bonus from the class) other than Thematic.
Personally, I'd take 19 levels (10d6 sneak, 4 special abilities) or go epic with it.
Monk - The only real reason to go heavy Monk is thematic. Sure they get minor damage/ac/speed bonuses, but not enough to justify the levels. Their higher level abilities are interesting, but again I view most of them as more thematic than mechanically useful (Timeless body, Perfect Self, Tongues).
Diamond Soul and Quivering Palm are only useful if you're going full monk.
Personally, I'd take Monk to 11 for Greater Flurry, or all the way for full monk.
Nephtys -
The template class from Savage Species gives the benefits of a template (like Half Dragon) gradually trough 3 levels. Since the Feral template can only be applied to a humanoid or monstrous humanoid I needed a way to apply the Half Dragon template afterwards. Normally the inherited HD template would be applied first and bestow the Dragon type on the character, barring it from taking Feral.
Actually, feral and half dragon are BOTH inherited, meaning you get to apply them in whichever order makes sense (You apply all Inherited Templates first, in ascending order). You can't apply feral to half dragon, but you can apply half-dragon to feral, so it works. Base human, add feral to become monstrous humanoid, Add half dragon to become Dragon type.
Except that feral's not allowed. Just thought you should know about the proper template stacking rules for the future.
Oh, and since my way to Pounce is barred with the Feral template will you allow me to take Pounce as an alternative Barbarian class feature with the Lion Totem (from Complete Champion)?
Well considering pounce is one of the reasons I dislike Feral, I'm going to say no to that. I'll fix Dire Charge so instead of just being during the 'first round of combat', it's 'once per combat', but I'd rather not see uber-charging every turn.
Are you still worried about what was bothering you in Dharuhks game? Opponents running away from you all the time? Cuz it's not something I see happen alot, and I've played/DM'd a pretty hefty amount of Epic.