Uh, well, you could look at Will Durant's 11-volume The Story of Civilization, which is a general world history for readers (though not for referrers). Or you could go for Burckhardt's Civilization of the Renaissance in Italy, which is a narrower study of the same subject.
Burckhardt is the original and still very good, but obviously dated. The Waning of the Middle Ages by Huizinga is a classic critique of the Renaissance period. Hans Baron's Crisis of the Early Italian Renaissance is a powerful argument about the Renaissance period. I'd also recommend John Najemy's A History of Florence, and Corporatism and Consensus in Florentine Electoral Politics. Two great reads are April Blood and City on Fire (both by Lauro Martines)--they cover dramatic events and the aftermath in 15th-century Florence. For more on Venice, try Frederick Lane. For Rome, try Kenneth Gouwens.