We've seen IllumiNations two ways...once in WS, and once from the cruise. My dh, who is not one for waiting around for anything, loved the cruise, hated the WS one. We had to stake out a spot and just hang there, in WS, for about 90 minutes. Dh and dd were not happy campers. But they did say afterward that they were glad I made them stay.
However.....last August we were lucky enough to get an IllumiNations Cruise. We shared with another dis'er, Hi Gail!!, and a family from our hometown. There were 6 adults, 3 teen-agers and 2 kids (10ish). We had plenty of room. Well, after I finally shoved over and made room for Gail's son (sorry I didn't move sooner Gail, I'm just a little slow at noticing stuff!).
We had a nice cruise down to MGM and then docked under the bridge. Yes, it was a little smokey. But it was smokey for the folks watching from the bridge too. We loved it.
Our party got off at the Int'l Gateway stop and walked back through Epcot and caught the monorail back to our resort.
We would not hesitate to do this again. It was soooo relaxing. I think the cost for the boat was $120 but we split it 3 ways so it wasn't too bad.