Sorry, but conditions of drapes closed vs. open for a week is too extreme. Given those conditions, I'd suggest plastic or silk plants. Otherwise, that's rather a tall order.

Things like Snake plants (Sansevierias) which can be fine in lower light, will NOT be fine in direct sun for a week.

AND also fast growing? Not too possible, seriously, plastic or silk. You seems pretty new at this, perhaps too new to realize the criteria you're giving make this VERY difficult to find.

Peace Lillies DO NOT do well in direct sun, recipe for a bad result, would burn badly.

New? How could you tell? :) I was hoping the Peace Lily would be too short below the sill to get full sun. I'll keep an eye on the room to get a typical idea of how often the windows are open or closed. I can control it to a point....closing the blinds when I leave if they're open. I think they're closed more often than not for business meeting purposes.

Personally, I think a snake plant could tolerate that situation.
Mine did fine outdoors in full sun last summer without burning, and they are known to put up with low light conditions pretty well too. My experience is that a lot of plants that are considered "low light" plants actually do well with more sun if they can get it.
The only problem is that I wouldn't call snake plants "fast growing". It'd be best to get one that's already about the size you want.

Well, the conditions do make it rather difficult.Parlor palm will be a definite no-no if you want something fast. It is a very slow grower and the prefered amount of light is bright and indirect. The best possible plant i can think of, which is very common in places like offices, is the schefflera arboricola. In good conditions, it is a fast grower. I would recommend all green varieties as they are less picky about everything, but variegated ones are much prettier. The plant adapts quickly to lighting, as far as i know it may be your only option unless you don't care if it grows fast.

Funny you should say the schefflera...because that is the plant I am taking home to salvage. They have neglected this beautiful tree till it's near demise. I have another post on this forum about it with pictures. My goal is to repair the Schefflera and then relocate the "new" plants I brought in. But I'm not forking out $50 for an office plant for a size I think would look best!

Eayeary. Unless a newly purchased plant is to be yours alone, don't blame you for not wanting to fork a ton of money.

Do you ever shop at Home Depot? Usually, HD has tall plants, 10" pots, for 9.99. These plants don't look their best, but not the worse-looking either. Most of the time they need a hearty drink, shower, 'remove dust,' and a little added soil. Of course, it's a good idea to check for plant bugs, but newly-shipped plants can have insects, too. In some cases, plant might need repotting.

HD usually marks down prices when new shipments arrive.

Large Sans, Dracaenas, Ficus, Scheffs, etc. 9.99 plus tax.

Because a window faces south doesn't mean the sun will burn plants.
If there's tall, nearby buildings, trees, any obstructions, southern light isn't all that bright.

For instance, 3 LR windows face south. Because of a large Pine tree and the neighbors' house, 'about 15' away,' the 3 windows do not get direct sun.

One window is packed w/Philodendrons. Some that'd burn in direct, summer sun, yet they do fine because harsh rays are blocked.

To be honest, most plants will not thrive if blinds are closed throughout the day. Even low light plants need sun.
If you're in control of blinds, 'depending which plant you choose to get,' you can keep blinds slitted or opened all the way.

One other thing. You're looking for a fast-growing plant. A medium light plant placed in shade grows slower. If it's getting medium, plus light it'll grow faster.

How often and long are meetings? Toni

Maybe consider getting a plant pedestal? This could open your options on what plant to have and it would also give you the height you want, without having to put it on the floor.