Complex sentence: With the advent of World War II, the Ritz was able to maintain a high occupancy rate but while business boomed, wartime shortages made it difficult to maintain the graceful living standards set by the original founders.
Split into simpler sentences: With the advent of World War II, the Ritz was full all the time. Business boomed but wartime shortages made it difficult to maintain the graceful living standards set by the original founders.