I tried to rewatch The Shield because I loved it the first time around but just couldn't get into it, but might need to revisit it.
Lost seems like a giant waste of time, it came out when I was in college and had no desire to sit around watching TV, saw a few episodes here and there but after hearing so much bitching about the final season, I'm glad I didn't waste my time.
The Wire is a must watch, it's not the fast burn of more modern shows and the switch from S1 to S2 is jarring but makes sense in the grand scheme of things. It's on my Mt. Rushmore of tv shows as well, along with Breaking Bad and the 4th spot changes from time to time.