HAL for Alaska CruiseTour?

I'm planning a trip for myself (28 yr. old) and my parents (60+) as a last family vacation before I get married. My dad is a very casual person (he loves to wear shorts all the time). I had originally planned to book with HAL, but then came across the dress code information. My dad would be willing to wear slacks and sport coat to the more formal events, but I'm a little concerned the atmosphere will be too stuffy for him and impair his ability to relax and enjoy his vacation. I would be most appreciative if folks could share their impressions regarding HAL. Also, we're specifically looking at the CruiseTour 6 itinerary - the 15 day cruise and land trip on the ms Zaandam. If anyone has taken this trip before and would be willing to share their experiences that would be very helpful. Thanks in advance for your replies and advice!