Sadly the MAX has had to put on special police and even consider abandoning their free fare zone due to many problems on the trains. Including several high profile assaults on board the trains; but these were all on the Gresham train (Blue line) and a different line (Red line) goes to PDX -- which has not had any problems. So, it cannot be said that Portland is any safer than NYC this year ...

The rest of the OPs plan is good, however I would highly suggest staying downtown instead of at an airport hotel. Portland has a very nice downtown, with great restaurants and entertainment and very walkable. Plus hotels at all price points; and the Sheraton is just a very ordinary airport hotel.