Great Generals in BNW

I gots one. What should I do with him?

In cIV, I would build his building, or bury him in a stack for safety. Now, I've just got him holed up in my capital, waiting for someone to invade so I can pick the right place to build his building.

But that feels stupid. SO, what do you do with your GG's?

If I'm at war, I use him with my troops. If I'm not at war, I make a citadel in a way that expands my borders around luxury or strategic resource that would otherwise be outside my reach.

I've seen the AI constantly use GGs to steal land from me if they hate me but don't feel like declaring war. GGs are useful for expanding borders onto something that's too far to tile purchase, and in fact, I once used a couple of GGs to steal land DURING a war to make my assault on his cities actually possible. Citadels are quite powerful, and as a Great Person improvement, they do increase tourism with the right WC proposals.

If at war, use them to support your troops.

If at war and desperate to establish a strong point (or you have one to spare), build the citadel.

If not at war, either keep them stored for future action or grab some land with the citadel. One can typically get nice firing spots near enemy cities...

I usually use one great general to support my troops.

One GG gets to sit in my capital, in case I screw up, and the front-line guy dies.

The rest I use to bust open those annoying choke points that happen whenever the AI gets some fortunate rivers and/or mountains.

I once had quite the epic slaughter against a technologically superior roman empire with my Zulu-Impis and a citadel, which resulted I a lot of dead romans.

Though, to be frank, using the citadel against the AI always feels a little like a cheat. The AI just doesn't acknowledge the damage that the citadel causes, since it apparently has not been scripted to be able to do so.

In my recent game Spain stole a Natural Wonder from a City State with a Citadel.
Thats a good use I think.