dunno if it’s just me, i’ve had a few people say they found Rome to be expensive but on the two times I’ve been I felt it was the opposite. Ok I wasn’t there for fine dining but decent pizzarias and bars were very reasonable. I guess you have to pay for the sights and things but like Barcelona I’d definitely recommend it for an affordable city break. Maybe I’ve just been lucky with the central areas I’ve stayed in.
Expensive places in my experience are Paris, Milan, Vienna, all Switzerland, Scandinavia. Cheaper places - Spain, Germany, Eastern Europe. Belgium and Netherlands are a mixed bag. Some places in France are more reasonable.