There have been a number of posts regarding places to find good quality Chinese sentences.
Well, here you go:
http://www.mnemosyne-proj.org/node/115
Over 20,000 Chinese sentences, organized according to HSK and vocab level. XML format. The quality of the sentences is superb. Beware the pinyin, though. There are some mistakes.
I just imported these into Mnemosyne and started working through them. They're good. Highly recommended.