the only "big" sportive I've done was one of the tour to Yorkshire ones, which was excellent, not cheap @ £60ish. It wasn't closed roads, but given the race was following us through and a lot was on country lanes, it was pretty much like being on closed roads and a field size that was sensible. Finishing down the official finish line on Scarborough front with cheering crowds, and a good turnout of support along a lot of the route did make it worth the money.
logistics were relatively easy as could drive to and from easily from where I was staying for the weekend.
I prefer either just riding with mates / OH, or a low key local charity event / sportive.