If you are trying to do micropower
design, then you want 2 things that I can think of:

- no gate leakage current
- transistors that have been properly modelled in the weak inversion regions and at micro currents.

Large geometry node, lets say 0.18 or even 0.25 micron or larger.

THis is thicker gate oxides and no get leakage due to that.

Transistor models will be what was created back then, you want BSIM 3.2 or newer.

Get foundry data on how the models were created.

Here read this:

http://chipdesignmag.com/display.php?articleId=438&issueId=16

I wrote that on the subject back around 2005