Made us some fresh maps! The most direct route from the TM/SM's house to the Peachtree boat landing is traced in red; it's 3.87 miles between the two locations.
The receipts in HE's car were a topic of discussion (until the news of kidnapping charges broke, lol), so I searched for specific locations of the gas station and the McDonalds visited on the 17th, and found this:
http://www.myhorrynews.com/news/crime/article_ada6ad1c-8f77-11e3-8ca7-001a4bcf6878.html
Mapping these locations, it's immediately obvious that the McDonalds is on HE's side of town, not the M side. Unless one or both of the Ms had some reason to be that far from home on the afternoon of the 17th, it seems most likely that it was HE herself who made the purchases. There are McDonalds locations closer to the gas station, so my hunch is that she either went home or was headed home when she decided to pick up some food. That particular location is a straight shot down River Oaks Boulevard from her apartment.
If the receipts are significant at all, it may be because LE found SM's or TM's fingerprints or DNA on them, proving his or her presence inside HE's car at some point between the afternoon of the 17th and the moment it was found abandoned.
Since Atalaya Place keeps popping up in the discussion, I marked it and measured the distance from there to PTL; it's nearly 11 miles between the two points. I really don't feel like Atalaya Place is relevant to the case for two reasons, though. First, because TM's online use of the name predates HE's disappearance. Second, why dump HE's car so far from her home in a relatively remote spot and dispose of her body so close to her home in a more populated area? Wouldn't make more sense the other way around? But a lot of things about TM and SM don't make much sense so, pffft, who knows?