WBJC - 91.5FM Baltimore
WBJC is the station to which I started listening since I've been down here in Baltimore. The selection is usually pretty good. They don't feature a lot of opera, though I don't mind as I prefer symphonies and other classical selections over opera. From the hours of 10am to 3pm Dyana Neal hosts, which is probably the best time to listen. Her selections are usually pretty good. The same goes for Judith Krummeck who hosts from 3pm to 8pm. So that's a solid 10 hours of good classical music daily. The programs that come on after Krummeck aren't bad, but sometimes it's a bit hit or miss.
To have a listen, go to their homepage [here] and on the left hand side at the top it says LISTEN LIVE, and click which is appropriate for you, either iTunes or WMP.
WQXR - 105.9FM New York Metropolitan and New Jersey
WQXR is the station that I used to listen to when I was up in New York. I still do on occasion. They do a lot of partnerships with the NYPhil and the Metropolitan Opera and sometimes they'll even broadcast some operas or performances live. WQXR plays more opera than WBJC and I think WBJC still has a better selection overall, but WQXR is still certainly a good classical station. They used to be on 96.3FM, but then while I was down here in Baltimore, or maybe when I was at West Virginia, they switched to 105.9FM and some Spanish station took their former bandwave and I almost died because I didn't know where they went until I found them on iTunes.
To listen to WQXR, you can either go to the Classical listings on iTunes Radio and find them. They should be listed as WQXR near the bottom. Or you can go to their homepage [here] and on the right-hand side at the top, you can click to listen live.