Thanks for your reply - I am aware that it's almost impossible to give precise answers given the nature of my question. However, I will provide more information on the board, and maybe that may help.
The core is a TI TMS320F2812 DSP, with an External bus interface. This is one of the biggest routing challenges I see, since the bus can't exactly be confined to one section of the board, since both analog and digital devices use it. For the analog devices, there is a 24-bit Sigma-delta ADC, 1 MSPS ADC, and 16-bit DAC, all with many opamps attached. On the digital side, there is Ethernet, USB, Modem, 4 UART's, PS/2 and LCD.
At this point, my biggest concern isn't really achieving ultimate precision from all the analog components. Due to my inexperience with a board of this density, I am more worried about proper placement of components, and things such as via sizes/placement and general good routing practice. Ground/Power plane layout is also proving to be quite difficult since we have Digital devices requiring 1.9,3.3,5 and 12V, and Analog devices requiring 5 and 12 (maybe). While I can confine most of the analog section to one side of the board, I can't seem to separate all of the Analog 5 and Analog 12V devices.
These are just worries regarding the PCB.. who knows if my design will even work