I would hold out for Mexico or the rumored Honolulu tour finale in April so you can experience the stadium staging of the show. Plus, I think over the next few months, you may feel sad reading about shows without knowing you have a show still left to see.
I went to the opener for Popmart in las Vegas and said to myself I would try to see the final show of that tour as well. many people went to the December 12, 1997 Seattle show since it was the US finale, but I skipped that show, knowing that I would see them in 1998 instead. It tuned out that the final show for Popmart was in Africa, which was a bit cost probibitive for me, so I ended up going to Japan instead to see U2, which was a country I wanted to see more than South Africa and I was also able to see the Rolling Stones there the day after I saw U2, so I was able to see 2 of my favorite bands in the same overseas trip. The show I saw in Osaka was the third to last show on the tour and it made me feel very happy to have covered almost the enitre length of the tour in seeing shows.
For Vertigo, I went to both of the tour openers: the real tour opener in Los Angeles on March 26th and the "official" tour opener in San Diego on march 28th. This time I've decided I will skip Portland, as I am going to go to Brasil in February to see the shows there and also plan to go to Honolulu if it in fact turns out the be the tour finale. If they do play there, then Portland loses some of its significance. It would no longer be the last Vertigo show in the U.S., it would then only be the final U.S. arena show and last show of 2005.