Some find that tobacco slightly lessens the benzo experience, so if you're taking them at low doses (or don't have lots available), you might want to reduce the amount of tobacco you smoke along with your cannabis.
As for the weed itself - some people find that benzos nullify the more pseudo-psychedelic effects of cannabis, especially with sativa strains, in an annoying fashion. This is true to a small extent. However, they will also effectively remove feelings of paranoia (if you are prone to such feelings) and definitely add some sedation and slight euphoria. It must be said, however, that as low benzo doses are quite subtle already as they are, weed can easily "overpower" the benzos so you can barely tell the difference - it changes from time to time and I'm not really sure if I think taking a low dose of a benzo with weed is nice or not. Higher-dose benzo and weed is great.
Benzos tend to go best with heavy indica stuff - gives you a really nice body stone and mental calm.