We were very happy with our hotel choice - the Residence Inn - Portland Downtown/Riverplace. It is right on the streetcar line and right beside the last stop before you leave the fareless square on the south end of the line. There is a nice Riverwalk area heading north from there all the way up through Tom McCall waterfront park clear up to Chinatown.
We were able to easily walk over to OMSI which is in a sort of out of the way place not on the light rail or streetcar line. The streetcar crosses the light rail line, so it was super easy to get to anywhere else we wanted to go.
Our room was actually 2 bedrooms, 2 bathrooms with a separate sitting area and full kitchen. There was actually a full refrigerator and a full dishwasher. There was even a table for 4 which really came in handy. It was very comfortable. The hotel had a very nice hot breakfast buffet that is included with the room which got our day off to a great start.
They also have a little grab-and-go area where you can pick up some things you need - like to address a late night ice cream craving! Another plus was the free wifi in the room. One of our favorite features was the pool which was never crowded and a great place to use a little time between activities or to make sure we used up all the kids energy before bedtime.
Our room was on the freeway side of the building and although the sounds did not really bother us, I would likely ask for a room on the other side next time. Something to consider if you are sensitive to sounds while sleeping. Besides that, this hotel is in such a quiet area, you don't get any of the city noises like you would closer to downtown.
*Note: I have written a bunch of posts about Portland so if you want to read more, click on the Portland Label at the end of the post, and you will see all the Portland entries.