Considering all the equipment mounted inside the suit, including the weight of the alloy used to manufacture the suit in the first place, what would be the approximate weight of a classic Iron Man suit?
Even if we don't consider the most unusual suits (such as the godkiller suit, the Galactus-buster suit, the LEGO suits, hulk-busters etc.), there are still probably more than a hundred suits in the comic books alone, with different equipment and capabilities.
If you want a single, base number, though... Marvel's site has some stats for Iron Man, including the following:
Weight: 225 lbs.; (in armor) 425 lbs.
So I would say that, in their current iteration in comic books, Tony Stark's armor suits have a base template weight of two hundred pounds. We can imagine that there will be some small variation depending on what he is packing for particular missions.