Oh, I know the bus well!
I've ALWAYS made my connection by giving myself about 1h20m.
I'd MUCH rather deal with LGA than ATL or RJs at CVG. Besides, with an upgrade, you can really enjoy the seat for a while on a long-haul FLL-LGA, for example.
That's not the the wackiest I've done in NYC though.
In fact, there have been at least 3 occasions in the past when I've been permitted to book DCA->LGA->JFK->NRT, SFO, or LAX. (NRT before Sept. 11, 2001)
In that instance, DL provided a car to take us from LGA to JFK!
We had to ask at baggage services... except the time we were in BE to NRT, in which case a red-coat was waiting for us and ushered us to a vehicle. That as nice.
Of course, I guess the cars and the red coats are now history. [groan]
Happy Saturday.