Proposition for future PGRE candidates: From all general physics textbooks I have searched till now, Halliday-Resnick-Krane or Serway's books are very good and sufficient (for the purpose of the test) as far as sharpening of one's problem-solving skills is concerned. However, if somebody of you want to cover as much theory stuff for PGRE test as possible using only one very comprehensive book, I propose to use the following textbook for your theoretical preparation
Igor V. Savelyev -> "PHYSICS, A General Course", Volume I, II and III
MIR PUBLISHERS, Moscow
This book contains only theory, not exercises. The first two volumes are around 450 pages and the third around 350 pages. The great advantage of this book is that it covers many topics that other modern general physics textbooks do NOT mention at all (for instance phase transitions, theory of rigid bodies -at an upper level-, basics of crystal structure and so on). This way, people do not need for example to read both Halliday-Resnick and Beiser and ... to cover PGRE stuff since all these topics are covered sufficiently (for the purpose of the PGRE test only, not for your qualifyings!) in this series I mentioned above.
For electricity, magnetism, electromagnetism and circuit theory instead of Griffiths' book one can read the more comprehensive book
-> "Electricity and magnetism", 4th edition, W.J.Duffin - it does a very good job especially for the theoretical preparation that is necessary for the test (for example, Griffiths' book does not touch topics about circuits that carry time-independent or time-dependent currents). This book places great emphasis on both the physical grounds that underlie concepts that are introduced in electromagnetic theory and various experiments that took place at the various stages of the develoment of electromagnetic theory.