We sailed on Millennium on a Vancouver to Alaska and back itinerary in 2009 in an outside view cabin.

A veranda cabin is nice to enjoy the views of the inside passage from the comforts of your own room. IMO, it's one of the highlights of an Alaska cruise.

I've never sailed concierge class or aqua class but based on the perks as others have listed, it's more worth it to jump from a basic veranda to an AQ class cabin.

There are different levels of drink packages. They offer a value proposition if you drink x beverages a day or value the convenience. You can also bring 2 bottles of wine aboard but will have to pay corkage if you have it served in the dining room.

As others have mentioned, there's no charge to sign up for a Captain's Club account so you really should sign up for it. You get some basic perks starting with your second sailing like some value coupons, welcome back party, etc.