Portland or Seattle...two great choices!
I have lived in both and being a condominium specialist, I know the condo markets very well in both cities. I have friends in San Francisco that sell condos and The Infinity is a great building. While I live and work in Portland. I will say the closest thing to this building will be found in Seattle. Not many buildings in either city will have the amenities like that of The Infinity. Most Portland high rise condos do not have large fitness centers, pools, theaters, courtyards, spectacular water views and concierge all in one building. Your best bet for this will be Seattle. With that said, not many in Seattle have all of the above in the same building. The closest thing will be Bellevue Towers in Bellevue. Two side by side towers..41 stories, a beautiful courtyard in the middle, a theater, decent size fitness room, concierge, fantastic Lake Washington views and a hot tub...sorry, no pool! In downtown Seattle your best options would be Olive 8, 5th and Madison, my favorite Fifteen Twenty-One and gaining a ton of popularity from the new popular book Fifty Shades of Grey, Escala condominiums. These buildings, especially Fifteen Twenty-One, offer spectacular views of Eliot Bay much like the views you might be used to with The Infinity.
As for Portland...here comes my sales pitch!
Portland is a wonderful city that is very walkable and I believe, much cleaner than the downtown Seattle area ( my opinion here) The Pearl District offers great dining, art, walking, biking etc. Nothing in the Pearl will compare to The Infinity but The Metropolitan would be your closest thing. Other buildings such as The Casey, The Henry, The Elizabeth and The Gregory are certainly worth looking at. In South Waterfont, Atwater Place will offer great water views but the amenities are pretty sparce in comparison. The developers in the Portland area did not add many amenities to the buildings if you compare them to the Seattle or San Francisco markets. The positive side of this is that your HOA fees will be lower than many of the buildings that have all of the great amenities like The Infinity.
Which ever city you decide on I think you will be very happy as each city has it's own unique characteritics that make them great cities to live in. If you would like to tour all of Portland's condos and lofts, I would be happy to assist you. If you decide on Seattle, I know of several real condo pros that I could put you in touch with.
Best of luck to you on your decision!