Sorry, I have no idea about where to get a massage. I'd call the hotel concierge. I'm sure they get that question all the time.
If you take the streetcar (there is a station just across and up the street, visible from the front exit and would be to your left), there are several downtown, south of the Pearl District. I have heard good things about the Rose Petal, but there are at least half a dozen others within just a few blocks. I suggest using the app (PDX Streetcar Mobile Tickets) for transportation and Google Maps if you are not familiar with the area. Bring comfortable shoes.
Massage Envy at John's Landing or Lake Oswego should be good. Personal experience w/ the franchise has been good, but none specifically at those locations. I'd beware of some "massage" places in downtown Portland unless you do your own investigating first.
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