Hi James. Glad to see you back on the boards.
I'm not sure for how long; I had a lull in my research. Hope all is well with all.
OK, Dread Necromancer route 1 -
Dread Necro 8 / Shadow Adept 2 / Incanatrix 10. Focus on metamagic which gives penalties to your enemies. Leadership later in the game for a Blackknight / Hexblade / Binder. You could easily be penalizing your enemies saves by -20 or so. Also massive bonuses for being a shadow weave user. This one's my favorite combo as its simple yet pure power, and very enabling for your party (DN's tend to be a glory-vacuum on the rest of the party once you get jut a few really meaty undead critters on your team).
Route 2 -
Dread Necro 8 / Pale Master 2 / Shadow Adept 2 / Lord of the Dead 5 / anything 3. For the undead mastery stuff.
Routes Insanity -
Dread Necromancer 9/ Ur-Priest 2/ mystic Theurge 8/ Dread Necro 10 (brokeny)
Dread Necro 2/ Binder 1/ Anima mage 10/ Dread Necro 3-9 (bindery)
Dread Necro 8/ Warlock 3/ Eldritch Theurge 9 (blasty)
Keep in mind that you could control around 800 HD of undead at 20th level when well equipped (this is a little bit of an overestimate). Lets say ALL of them require the 50 gp / HD component cost (which they won't). That will cost you 40000 gp. Which is only about 10-20% of your wealth at that level. Is that worth the Pale Master cost of a caster level and delayed progression? I say no, but its up to you.