Alright, I looked up his stances on some issues:
http://www.ontheissues.org/Mark_Warner.htm
What I like:
His support of fiscal conservatism
His record on fiscal results in Virginia
His support of increased minority police and ending racial profiling
His idea to focus juvenile justice on workforce training (I really like this idea)
His support of promoting competition and choice in public schools
His belief that economic prosperity depends on wise use of natural resources
His support of free trade, and his belief that China's human rights record should be considered in its MFN status
His support of the second ammendment
His support of homeless job training
What I don't like:
Extend hate crimes (wherever they're being extended is irrelevant, hate crime legislation is stupid anyways)
His support of the death penalty
His support of the elimination of parole (when taken along with

His support of increased penalties for illegal drugs (what, should we just build more prisons?)
His support of a minimum wage increase
His belief that the government should fight against internet pornography
Other things I either don't know enough about to have an opinion on, or I'm just not a huge fan of his stance, but I don't actively dislike it.