I usually do a scan of port schedules to see how much competition there will be when we're in port. The information I get is never certain but is a good guide. Here's what I've found:
Aug 10 - Victoria - Carnival Spirit.
Aug 11 - Vancouver - alone! Surprising. We boarded there last September with 4 ships in port and it was a zoo. We had priority boarding but It took 3 hours to pre-clear US Immigration.
Aug 13 - Juneau - Celebrity Eclipse.
Aug 14 - Skagway - Carnival Spirit, Carnival Miracle, Norwegian Jewel. The tours and town will be busy.
Aug 16 - Sitka - alone. the Sitka stop is one reason we're taking this cruise.
Aug 17 - Prince Rupert - alone.
Aug 19 - Victoria - Star Princess.
I'm planning to talk with our TA to see if we can switch to VIctoria boarding, but I've noticed that the Aug. 10 Victoria boarding is no longer available on Cunard's website.