I found the Omaha and Phoenix just painful, pick your fights, go for other cruisers and destroyers, go for BBs if you can gang up on them.
Keep going with the US cruisers though as the Cleveland is frankly OP at the moment and once you've skilled up enough to boost your secondary/AA ability you can really help out your team by escorting other ships and shooting down loads of planes.
The Pennsacola is a bit weaker than the Cleveland due to its paper thin armour but I'm up to New Orleans now and finding the 203mm are accurate and pack a decent punch and some of the survivability is back. Can't wait for the Des Moines with its 6 second reload though