Holiday Work Parties-What to Wear?

So, I don't actually have my own work party to attend this year as I work from home as a daycare provider (so, you know, everyday is a party!) but Dallas does have one.
He works at a BBQ place in town, it's individually owned so it will be a small cast of players at this thing which I find a bit daunting because that puts a lot of pressure on everyone to be nice, funny, and on their best behaviour.  Booooo....
What does that mean for me? I don't know.  I'm still hung up on what I'm going to where.  TV shows, movies and even YouTube tells me I'm supposed to wear a sequined dress or a red scarf or a bright Christmas sweater but...I don't know.  It's cold as fuck here so I probably don't want to wear a dress anyway but I do want to look nice and casual.  Dallas thinks pants (which is pretty obvious if I'm not wearing a dress/skirt) but not jeans (duh!) so that leaves me with my Guess tight-ass waxed black pant (literally NOTHING left to the imagination--"say hello to my pubic bone") or sexless black dress pants from the Gap.
I kind of want to look somewhat cute and maybe we will go out to a bar later so I'm thinking the Guess pants, but then what on top?  A sweater?
I guess I should tell you the venue first: we are going to Saboroso, a "brazilian steakhouse" that's just up the street from us.  It's expensive there, so, you know, kind of swank, but it is just a restaurant in Saskatoon so not that fancy.
So sweater?  With a tank underneath to wear out later?
Or maybe my sleeveless blouse I just bought at Garage (I know, shudder, it was a storm and there was nothing at the mall closest to us but this) to wear to the Big Wreck concert last night:

So, I would pretty much look exactly like this model, except I'm prettier, skinnier and my hair is shiney-er.  You know, whatevs.  I wore it with dark denim last night and these boots from Spring:

But to Dallas' thing I don't want to wear these boots so I'm thinking either leopard flats like these:

or my stilettos like these:

I dunno.  I really don't.  Do I play it sexy or not?  Dress pants or tight pants?  Dress pants with heels or tight pants with flats?  Or tight pants with heels?  A sweater like this:

of which I can wear black pants and heels and my necklace like this:

and make work.  I dunno!  I could wear the heart shirt underneath it and take off sweater later if I want?
I hate making these decisions.  I feel like I'm not playing with a full deck of clothes already.
Let me mull this over and I'll get back to you.
Any thoughts you have in the meantime would be much appreciated.
xoxo
Roxanne