We have done both Illuminations and Wishes. Family vote showed preference for Wishes.
Get there as soon as the marina opens that evening and they will generally take you out early and drive around on the water.
For Illuminations, we left from Yacht and Beach Club Marina. Walked over from Epcot.
If you do Wishes, I recommend getting the music piped in (all have this except for the smaller boats). Also, if the timing is right they will take you out to see the "light show parade" that performs in front of each of the waterfront resorts (Grand Floridian, Polynesian, etc.) about 9:00 each evening. If you are staying at any of these resorts, head down to the dock/beach to watch it if you are in that evening. For Wishes, we left from Grand Floridian. You can take the resort monorail from MK.
Each cruise had soda and water. Snacks were chips, pretzels, etc. You can cater in a meal through them if you like (we didn't, we usually have an ADR before).
They also offered anniversary decorations (balloons and such) for $25, but we declined so I don't know what they are like.
Since these leave from a waterfront resort rather than a park, you don't need park tickets. Might be an option for one of your "off" days. Also since there is a fixed price for the boat, you can invite friends who live in the area to join you at no additional cost since they don't need a park ticket (just make sure you know how many the boat holds). When they say the boat holds 10, it is probably a pontoon. Comfortably fits 8 adults, but you can fit 10.