When the ULA Vulcan was first announced, the plan was the engines, which are 90% of the cost of the first stage, would be recoverable and reusable. The idea was the engine section would detach from the rest of the rocket, fall a ways and then a parachute would open, and finally it would be caught mid-air by a helicopter. The idea was this would help it compete on price with the Falcon 9.

However, according to the Wikipedia article on Vulcan, this has not been funded, and so the rocket is going to be fully disposable.