If I may, I'd like to add a tabletop element: Perception Check. Anytime you'd like additional info about your surroundings, [u]underline[/u] your words requesting it, and my next post will provide info about what your character can perceive at that moment. So for example:
_

[i]
Player:
John Doe walked into the room and ran his hand through his hair. He'd been trying to [u]find his whiskey[/u] all morning, and expected to find it in his study.

GM:
Unfortunately, there was [u]no whiskey[/u] in the room. It seemed different somehow- cleaner, like someone had gone over it with a duster. Perhaps that person took his whiskey.
[/i]
_

You could also ask straight-up. Additionally, I can mark important choices with underlines. For another example:

[i]
Player:
Sir Knight [u]looks[/u] around the lobby at [u]nearby people[/u] as he heads further inside the castle.

Where does the lobby door lead?

GM:
Most of the folks in the lobby are servants, though one of them is a [u]striking redhead[/u] in a healer's coat. She is doling out potions. The lobby door leads to the Great Hall, where the dances, banquets, and public ceremonies are held. There are actually several doors in the lobby, and the guard looks like he [u]would rather you didn't wander off[/u].
[/i]
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Don't worry about post lengh. I would much rather see players make short & interesting choices than long-winded & boring ones (if you can only do one or the other). I can still get a kick out of a great one-liner, and sometimes just a few words are all that's appropriate. Remember, this is a Casual RP; don't feel obliged to write a novel every time you post. :P