we have done all the Waikiki boats. I would agree on the Maitai, its the best choice. The boat is very clean and sails very well and has good seating. The best party boat is the Na Hoku II with the red and yellow sails, good for the 20-30 crowd. Done the pirate boat and it was pretty fun, they leave from the Marina across from ala moana mall, perfect for 10 year olds, they have a groupon but be careful it is for usually Hawaii residence only. The Hilton has a Hawaii Nautical but it is very over priced.
Day sails are the best for families and are cheaper, the sunset sails tend to be all you can drink, so expect a lot of drinkers, I have gone many times and they can be really fun.
Waikiki is protected from the wind by diamondhead, so it is very calm until they get past diamondhead. That is where it gets the big waves, they will go out there crashing thru them, and its part of the fun and you will get wet if you sit in the front.
Its common to see turtles on the way out, they like to swim along the coast, you can see whales in the winter and a occasional dolphin group.
Sunset sails on the Maitai sell out maybe a week in advance, day sails a day or two, and you can reserve online. Na HokuII takes reservation the day of the sail on the beach but will be sold out by the end of the day, and its cash only
leahi.com nahokuII.com hawaiipirateship.com
Very good advice about making sure you go to the correct boat, there are 7 on Waikiki beach.