Take this knowing that its been almost 7 years since I did any training in a GA aircraft, but $70/hr sounds a little steep - unless you are training with a Class 1 Flight Instructor - but PPL means youre probably with a Group 4 or 3, so yeah that sounds steep.
Remember though that the cost goes up with the type of airplane, so if you have decided to do training on a fully packaged Cirrus or one of those nice new computerized 172's then you may end up paying a little more than if you went down the road and flew a 152 or PA28 - at the end of the day you are not more employable to an airline if you have EFIS training on a 172, because the Navajo or King Air you will start on probably is more than likely steam driven.
As for 2.3 hr brief sessions - I did the instructor thing and I always briefed about an hour per flight - half before and half after - and yes you want those brief sessions because you need to understand how and why you are doing a specific type of training, and how you did on the excersie - but I do question the logic behind waiting two flights then doing a long brief. Is it the same topic for the same 2 hours, or does your instructor cover all the subject material from your previous flights?