how to watch parse/plan trees

How do you people look at various trees and lists when debugging them ?

Do you 

1. use functions from nodes/print.c to print out tree snapshots

2. run the backend under visual debugger (like DDD) and look at things
there

3. memorize everything in binary and work on raw memory image from
/proc/core ;)

4. use some other method


I am currently working on understanding enough of the parse/plan/execute 
process to make up a good plan for implementing WITH RECURSIVE ...
SELECT ...
and perhaps GROUP BY ROLLUP(a,b,c) from SQL99 spec and I'm not
proceeding 
as fast as I'd like ;-p

Also could anyone recommend any tools for debugging gram.y or is this
also 
done mostly by hand even for large grammars ?

------------------
Hannu