I've taken 2Hip2BSquare's map and added to it a bit. I traced the speculated route that AS could had taken.
I think that it's entirely possible that AS could had gotten on to 1st from the site of her accident. Regardless of the accident's actual location, she likely did not obey street signs in order to get her car out of the way. She would had then continued west on 1st, coming to Roosevelt, turning south and attempting to head toward 5th street. Roosevelt is more residential than Farmer or Wilson (her first two turn options) so I could see her believing it to be a safer, more quite place to turn in the middle of the night. What I wonder about, however, is how she managed to drive that distance with two popped front tires, like the rest of you. If she could had gotten as far as they say she did before dumping the car, I feel she could had gotten all the way home with the car. They seem natural paths to me, though why the car was said to be left at the Roosevelt/Brown location and why she chose to meet the cab at AM/PM baffles me also. Speculating only, but perhaps both are red herrings. Regardless of when and why, I feel that AS would had stayed along the streets that I pointed out on the map.
Most simply put, with the information we are given and assuming the red herrings are nonexistent, this is how I speculate things went down:
1. AS attempted to get to boyfriend's home going NE from her apartment to Rio Salado.
2. Here, Ash and Rio Salado, AS experienced her accident and "took off" on the shown route in attempt to get back to her home with her damaged car.
3. Once she reached Roosevelt/Brown, something prompted her to get out of her car and/or made her believe she could not drive it any further. Perhaps this is the first time she was calmly able to stop- she would had then assessed the damage and decided to leave the car (in a seemingly safe spot) and carry on by foot.
4. She walked from Roosevelt/Brown to 5th Street, went to her apartment, changed her clothes, called for a cab to meet her at AM/PM.
5. She left her apartment, hoping to take either 5th to Hardy (passing Jaycee Park) or Hardy directly. This is where we lose track.
I hope this seems clear and accurate, please let me know if there are places to revise.
I drove the area a bit yesterday afternoon. I saw around five posters. Only police presence I was aware of was one police car at a complex on Hardy.
To clarify what I can come up with in regards to the "forensic vans," it was a completely unrelated comment upon the atmosphere of the valley as of late and the location was assigned to Mesa, not Tempe.