Well, the first advice I have, is next time invite your girl friend to go shopping with you, it's always good to have a second pair of eyes around while shopping, plus she wouldn't feel left out, which I suspect is the real reason for her unhappiness...
Second - almost all guys I've met looked good in a pair of levi's 501, this is a totally average pair of jeans that's totally classic and not fashionable and just look good on almost anybody. If you don't have a lot of clothings and just want to very - I would avoid patches, glitters, artistic needle work and other decoration and just go with "classic" and "simple"
Third - get the right size! it sounds simple, but this is the most common mistake people do while shopping for cloths (me included) a lot of guys tend to get a few sizes too big. (skinny guys want to hide the fact that they are not buff enough, fat guys want to hide their bellies) - this does not work, and in most cases would get you look more skinny or fat. If you have doubts about your size, ask the store sales person.
Also - I would avoid black or white jeans or the very light blue, those colors comes and goes in fashion, while dark blue is always in style.
most sites I found about perfect fit jeans are for women, but maybe you can find some helpful tips:
http://www.wnetwork.com/articles/styleT1.asp?id=452
http://www.greatestlook.com/advice/jeans.html
This one's for guys!
http://omiru.com/index.php/2006/08/17/david-lim-of-kasil-jeans-how-to-choose-the-right-pair-of-jeans/
http://www.arabia.msn.com/Family_Home/fashion/Men'sfashion/rightJeansforMen/
http://www.gopilipinas.com/magazine/men-Fashion/Fashion1.htm