One thing I wondered about in this case was, "Where did the victim come from before checking into the hotel?" I noticed that there was something like less than an hour difference between when she made the reservation and her arrival by cab which suggests she was not from the immediate area. There is a ferry terminal (with daily service between Seattle and Vancouver B.C.) about 2 miles away and its not uncommon for taxis to be called to that area for pick-ups... So that might support the idea she came from Canada. On the other hand, if she arrived by SeaTac airport, her taxi ride could have easily been an hour... Additionally, in the baggage claim area of the airport, there is a large phone kiosk with direct connections to the area hotels - including the Vintage Park Hotel? There are also several ATM's in that baggage area where she could have withdrawn cash for the taxi ride and hotel stay.
But why that specific hotel? It is neither the largest, most luxurious or even most affordable. There are several other hotels within a 3 mile radius that could have just as easily been chosen. Maybe it was the quaint charm of the hotel that helped the decision? Maybe it was chosen not for its amenities but for its proximity to another landmark within the city of Seattle? Directly across the street from this hotel is the U.S. Federal District Courthouse property - landscaped with 4-5 very large Maple trees. During warmer months, it is not unusual for large numbers of office workers to use the adjoining lawn for a quick lunch or smoke break. The material we have indicates that the weather was unseasonably warm when "Mary Anderson" checked into the hotel and that the investigators found a maple leaf in her room pressed between the pages of the "Seattle Weekly"... a local paper found in amongst the newspaper vending machines in front of the same courthouse. So we can at least casually link her to the approximate area...
A couple other thoughts: Many folks have commented on the style, type, and volume of clothes she had hanging in her closet.... I'd suggest that these weren't "travelling clothes" but rather clothes appropriate for a public forum... She had a heavier blue coat and gloves - not something a local would packed given the warmer weather. Why so many if she only had paid for a couple night's stay? And why did she have an iron? The fabric of her clothes isn't the type to be ironed - dry cleaned more likely.
Here's my amateur theory: Mary Anderson was in Seattle to see someone who was going to be in Federal Court for a trial. She had brought along several different outfits that could be worn interchangeable (all "jewel" colors?) because she didn't know exactly how long it would last. The iron was for the clothes not in the room: A dress shirt and suit pants perhaps for a male defendant? Prisoners often rely upon their families (through their attorneys) to drop off "court clothes" to make themselves more presentable during a trial. Making sure that such clothes were neatly pressed seems to fit in with the other aspects of the orderly nature surrounding "Mary." Having such a male in her life would also fit into the findings of the worn IUD?
I wonder about the lack of identification and the lies she wrote during check-in regarding her residence. Positive ID wasn't required for either airline or ferry travel in those days but still there should have been something? Here's another (kinda) far-fetched theory: Mary was very careful about her ID because she didn't want anyone (particularly people in a courtroom - like Federal agents) to know her identity if she was stopped outside the court.... Perhaps she (mistakenly thought) she was also wanted or would be questioned? It is also a particularily common concern and tactic for suspects/groups who see the federal government as overly intrusive or controlling (Freemen, Posse Comitatus, etc). If memory serves me correctly, there were several of those types of cases being processed through that specific courthouse during the same time period. Immigration case? Border smuggling? Those are relatively common for the court, too.
Assuming she brought the poison with her, it seems reasonable that her death had been planned for some time... Can any significance be placed on the exact day/time of her suicide? Following along with the above theory, was a conviction a near certain and it ended after only the second day? The only way I think that would be possible is if the defendant decided to plead guilty on the first day (not uncommon - particularly when prosecutors offer a "last chance to plea" in exchange for a lighter sentence). Or maybe Mary knew someone who was to be sentence and she wanted to see him for one last time before he went away? That would still fit for the iron/clothes part of the theory... Did she then kill herself because she didn't want to live alone without him? Was this a case of falling in love with the "wrong guy" and that's why she wrote that it wasn't anybody's fault... that "it" (the way things had turned out) was her own fault?
Okay - that's enough speculation from this amateur!