Shortly before retirement i was somewhat peeved when a 747 was substituted for a 73. Nothing in the plan and as it was busy I happily vectored another 73 five miles across behind him. Only afterwards did I get a lecture - on a busy freq - from the captain of the second a/c complaining about wake turbulence. The annoying thing was was that he had visual contact with his traffic and I'd also given him traffic info clearly stating "another 737" . In non RVSM airspace so he could have eased up 100 feet and missed it