What settings are best converting avi to mpeg2 for dvd authoring

I was wondering... I have some good quality avi files and I want to know what settings would best optimize quality and size for DVD authoring. i.e. size I usually just use 720x480 . frame rate I try keeping the same as avi if known (thought it might speed up conversion?)although I run into issues sometimes and and end up having to use a pulldown. 16x9 aspect. usually use a vbr 2000-3500 2750 avg.kbp/s. wondering though if a movie like saw (dark & strange lighting)should i use a cbr because it seems as though the program might see those scenes as less dense and slower and therefore use the lowest bit rate in those scenes when it should probably use more to avoid that digitized black blotchy look, hard enough to see those scenes as it is.

Can and should I change some settings are there dvd standards. my avi's are about 700mb divx/xvid per 100min. I like to put 2 of these files on one dvd.

 

What program do you use for your conversion?