From an interview Wired did with Evan's friend Jeffrey O'Brien we know Evan and Jeffrey were in San Francisco on August 12th. Jeffrey states:
Evan's Fast Track toll pass has him leaving the San Francisco area on August 13th at 7:27 p.m. So, the "day before he left" remark by Jeffrey fits in with Evan travelling to Las Vegas and selling his car on August 14th. Evan, who is nocturnal, could easily have driven to Las Vegas in 9 hours, spent the night in Las Vegas, and sell the car on the 14th. It's also possible Evan could have stayed some where in between San Francisco and Las Vegas.
"The day before he left, we watched the Mexico-U.S. soccer match in town, and he told me that he was leaving the next day. But he didn’t say anything about where. He was driving his hunter green Honda. But he told me that he was going through a move and selling that car. But he certainly hadn’t sold it yet."
After the 14th, Evan pops up on the grid August 20th using his computer from San Diego. Then on the 21st of August he makes a deposit at a ATM in Santa Monica, CA. There are no confirmed locations to my knowledge between the 14th in Vegas and the 20th in San Diego.
This is my best guess as to confirmed locations. If you have any additions or deletions, please leave them in the comments.