Unmentioned in your 99W history is how 99W used to run up North Interstate Avenue, where it connected with I-5 and in a kinda-sorta way with 99E before crossing the Interstate Bridge. What was once a 4-lane city street is now 2-lane with a MAX line.
Had you driven on the Fremont Bridge, you would have encountered the US 30 West interchange, which leads to a very short stub of freeway that would have been the start of I-505. That route along with I-305 in Salem, which was superseded by the Salem Parkway, were two urban Interstates that were never built.
Looking at the pix shows you were extremely lucky to not encounter congestion. Portland is infamous for jammed up freeways.
Going east of the Morrison Bridge will quickly let a person see the Morrison Hotel. No, it is not named after Jim Morrison...LOL! Still, there is a bit of fame due to The Doors attached to that place. Unfortunately it is no longer a hotel and the bar located in the building has closed.
When the Baldock Freeway was built, it was numbered at US 99. There was still US 99W and US 99E, which may have resulted in the only triple layer of highways with the same main number. I-5 north of I-84 was called the Minnesota Freeway. Go figure!
SR 217 did not get a full freeway interchange with I-5 until the last decade if memory serves me right. The previous interchange had traffic lights to deal with before getting onto the freeway section of 217. Massive congestion back then. Today with the full interchange being present, the congestion is still massive. Sometimes you just cannot win!
Too bad you missed out on the picturesque sections of 99E. That part of the metro area is the easiest to drive. Busy but not overwhelmed makes this main route the best one for getting around Portland. One can then choose which bridge to cross the Willamette to access the west side.
91 KISN (910 AM) back in the days of the Boss Radio format, was able to capture 85% of the radio listeners in Portland. Yeah, it really was the boss! Today the callsign goes to a low power FM station that only has 2 watts of effective radiated power so all of the Portland area is not covered. What a change from those halcyon days!
https://en.wikipedia.org/wiki/KISN_(Portland)
Hope you enjoyed your time in the Rose City Max and that you like a light rail system with your name on it!
Rick