I have recently done a dynamic simulation with a skirt on the figure sitting on the chair (in Poser 10).

One thing to remember is that you don't need to do the whole thing in one simulation. I did the sitting pose without the furniture first to get the skirt generally folded over the lap; saved the results as a morph and deleted the simulation. Then I did a new simulation that put the figure close to the right place on (but not touching) the furniture; saved the results as morph and deleted the simulation. Then I did a final simulation just for a final drape (saving as a morph).

Splitting it up into separate simulations lets you change settings and change constrained/correographed groups for different pieces of the simulation. It also reduces the chances your computer will choke on a simulation that tries to do too much.

Be careful of how the skirt will get pinched between the figure's bottom and the furniture. It probably helps to set the friction numbers for the furniture low so the skirt doesn't get snagged on the furniture.