When I go to Rome next month, I'd like to sample a variety of Italian wines. I like wine and have some, but not a lot of familiarity with Italian wines. I was thinking a wine bar might be the best bet, since you can order by the glass. Since I don't have an unlimited budget, is the house wine usually a good choice in trattorias? I'd appreciate any suggestions on how to go about trying different wines, and where to start!