Genkai 65 is fairly easy, but is long and you will need higher level players to help with mob control, since you will be going into areas where 99s still aggro. Below is a link to a very detailed walk thru.
For the Yag Crest, I've always worked with 1 other 99, we clear the Yags out of our path on the top floor. This is the floor where the contraption to input passwords into is on. If you work quickly, clear a path to one torch, you can get into the password room aggro free.