Norman Davies: God's Playground a History of Poland The Origins to 1795 (Oxford University Press 2005)

Daniel Stone: The Polish Lithuanian State 1386 to 1795 (Washington University Press 2001)

Those two books are two of the most popular/well known and easily readable works in english. Both have very extensive bibliography sections which should help you expand your search.

The Davies book is a 2005 re-issue adding a chapter about Poland joining the EU (the book has two volumes), so any edition of the first volume will be sufficient.