Razing any city with less than 4 recouces? This is madness!
I can come up with a hundred examples of a city with less recources, and no wonders that I wouldn't raze. This doesn't sound like quality advice. The only time you should raze cities that are not totaly junk / settled in the wrong spot, is when you want to win conquest with a decisive early rush. Something about the opening post makes me think Shudz is not aiming for a 1 AD conquest victory here.
Depending on how fast you conquer, if you don't want to tank your economy there is a maximum number of cities you can handle. If you are conquering a lot early and keeping all cities that you would want eventually (because they do have 1 or 2 resources and are placed correctly, but don't have any especially good reason to keep them) you can easily overexpand, come into a slump, be very technologically backwards before you get out of the slump, and lose the game.
In particular you should have a higher bar than "cities that are good" for keeping cities if you conquer a lot of them. You don't settle all possible cities of that level immediately either, do you? The bar is a bit lower than "cities I would settle right now" since keeping them now saves you the cost of a settler, and you may have some bonus buildings/pop to start with. But it is certainly sometimes wise to raze perfectly placed cities on average terrain (of a level that you'd settle them eventually to not let the area go to waste), to avoid overexpansion.
The important question you need to ask yourself is what the goal of the war is if it is not getting those cities. Gaining an early conquest is one possible answer, but clearing the land for later expansion, removing a neighbor who is bound to misbehave, or getting some awesome cities are also valid reasons.
Perhaps my advice was a bit too exaggerated, but the point is: razing awesome cities is almost never a good idea, while, if you anticipate an extended conquering push you should raze perfectly alright cities with a view of resettling them later. The latter only happens for me with rushes with very good offensive early UUs, such as the praetorians, quecha's and immortals on not to high a difficulty level. Since the OP was talking about using preatorians on monarch and razing everything in sight to avoid overexpanding, I assumed his attack would not stop at Paris.
