We just came back from the Canadian cruise. We sailed Sept. 17th. It was beautiful and we had a fabulous time! We sailed with our three tween kids. They loved Camp Carnival and Circle C, even though there weren't very many other children sailing. We did find that Camp Carnival and Circle C weren't always open when we wanted to use them (because there were so few kids on this cruise), but the kids had no trouble having fun elsewhere on the ship.
We were determined to use the slide on the ship even if it was a little chilly, and there were 3 days when we used the slide. If it's too windy Carnival keeps the slide closed, but it was open three days. The first two days we had rain so we spent time exploring the inside of the ship and/or ports on those days. We set out on this cruise to have fun, so we looked at the weather as an adventure. The slide was a blast and there is no line for those brave souls who try it this time of year. And then you can hop into the hot tub afterwards. :)
I told my kids at the beginning that they wouldn't be using the arcade, so they didn't ask. However, when we walked through the arcade there was nobody using it. Because of the time of year and relatively few kids on this cruise, I don't think the arcade got used much. I have read that kids who do use the arcade can easily spend $100 there because the games are expensive. There were video games in both Circle C and Camp Carnival that the kids had fun playing.
The soda issue ended up being a non-issue for us. The Lido buffet offers lemonade and iced tea. Soda requires a special trip to the bar (I think - we never bought soda), so my kids were quite happy to have lemonade. At the formal dinner we all had water. Sometimes DH and I had a glass of wine. If your kids do have soda with dinner, it is only $1.95.
The hair dryer is like a hotel hair dryer. I brought my own.
It's true what they say - having fun on a cruise has a lot to do with your attitude. If you set out to have fun, you will, no matter the circumstance. The shows and comedians were amazing. We were so busy having fun, I didn't even sit back and read the book that I'd brought.
How much spending money really varies. We didn't use the casino. We spent about $10 per day for DH and I on drinks. I spent about $100 on photos. They have great photographers on board and it's nice to have some good memories to take home.
I was anxious before we left, too - not sure what to expect. Canada and Maine are gorgeous this time of year. You will have a blast! Have a good attitude and avoid complainers. :)