For your information, here is another number of US cities Stars on Ice visited during the spring tour. I reconstructed this info using archive.org material, so accuracy cannot be guaranteed.
Concerning the winter tour:
Usually there was one or two shows around New Year Eve in Lake Placid and vicinity. One year they had Sergei memorial shows instead of usual Stars on Ice show(s) with SOI alumni.
Sorry, I missed the "spring tour" part. For years, Stars on Ice had rehearsals for weeks in Simsbury, CT (either Sep or Oct, I forget which), then another couple weeks in Lake Placid, before premieiring the show Thanksgiving weekend in Lake Placid. Then the full tour kicked off around the New Year (when it was 60+ cities, it kicked off around 12/27, and then started moving to early January, and then mid-January, and then February by 2008 or so). They only started doing the New Year's Eve "holiday" shows in the 2011-12 year, I believe, after they finally stopped going to Lake Placid at Thanksgiving. So I'm not used to thinking of it was a winter vs spring tour. It used to all be one tour! Though, wow, where did the last 8 years go?
I heard the tour started to dwindle after Mr. Hamilton retired, which happened at the end of 2000-2001 tour.
That's possible, though it took a few years for them to finally cut back on cities (see above). I believe they tried hanging the tour on Tara Lipinski but she left the tour after 2002, and then they tried to play up having both Sale & Pelletier and Berezhnaya & Sikharulidze on tour after the 2002 Olympics. By the 2003-2004 tour, they turned to having a slew of guest skaters who were former SOI stars (Kurt, Scott, Paul Wylie, Oksana Baiul, Katia Gordeeva, Kristi Yamaguchi) to help boost things, which was a change from the stable cast they used to have. But I guess those strategies all didn't work that well. I believe there was a lot of blame on the 2002 SLC Olympic judging controversy for lessening interest in the sport. Who knows if that was true.
For those who are curious, the relevant links on my site:
http://kurtfiles.com/soi/history.php (sorry I stopped updating this after 2013)
Concerning the Canadian shows:
I remember the number of Canadian shows has been quite steady, around 12.
Yeah I don't think that has changed much over the years, just which cities were in the middle of the 12.