What should I get???

You've got the sports covered with the 70-200. On DX a 50mm will do the portrait thing. Adding a 85mm will give you some benefit in Bokeh, but it's usefulness depends on what type of portraiture you are into. Head only, full body or torso? And of course the distance to your subject.
I'd consider the 85 1.4 for it has a creamier bokeh than the 1.8.
Choosing between a D300s and a D90 is quite easy for me. The D90 would make a great back up body or good looking paperweight.

Not to be snide or obnoxious, but if you have to ask....
What does your current kit limit you from doing? If you did more landscape, I could see needing something wider in the lens line. IF it were me, I'd keep the D300s and dump the D90 and buy the 12-24 f4, or just buy the 12-24 for the d90. Personally, I like the faster shutter speed, 100% viewfinder and fps of the D300s. But that is me.

I think the 85mm f1.8 would fit in there nicely for portraits along with the 50mm. It does not hurt to have two camera's and sometimes the lighter weight of the D90 will be just the ticket.

Are you saying you are returning the D300s? It is in a different league than the D90; certainly not a replica of. Not saying the D90 isn't a good camera but the D300s is a superior camera. In terms of lenses, do you find yourself wanting to shoot @ 85mm with a wider aperture? You have the FL covered @ f/2.8 with the 70-200. I would probably look at the Nikon 17-55 or the Tamron 17-50.

With a 70-200 I`d not be interested on a 85mm lens... the prime is more than one stop faster but, how many pics will you take at f1.8 and not at f2.8? If you need a lighter (consumer) lens, then it`s ok.
Looking at your gear, I`d miss something to shoot indoors and for all-round use.., I agree with Douglas about the 12-24. Just add a 35/1.8AFS for casual shooting and that`s all.

Exactly what type of sports do you shoot? AF on the D300s is considerably better than what is on the D90, but only you can tell whether that will make a difference for you.

Concerning lenses, do you have any wide angle? If not, that seems to be an obvious hole, especially if you are now into landscape work.

Andrew, the image quality of the D90 may be the same as the D300s, but the D300s does have more going for it. the 51 point AF would actually help you in sports shots. the faster frames per would help in sports shots as well. I own a D90 and love it - but I do not shoot sports. I also would not buy a 85mm since you already have the 70-200 2.8. I probably shoot 1/3 of my portraits with it, the rest goes to the 50mm. if you do not shoot landscapes a wide angle will see limited use IMO. honestly, If I was in your shoes I would keep both cameras. have the 50mm dang near permanently attached to the D90 and the 70-200 attached to the D300. The do D90 could go everywhere with you and the D300s could be used for sports jobs and photoshoots. just my 2 cents

For sports, you will miss the D300's AF system which is the same as the D3.

I have to agree with so many here. You're going to get rid of the D300s & you shoot sports??? That's an interesting way to go about things. ;-) The D90 can't hold a candle to the D300s for sports.
Ah well to each their own.
As far as I'm concerned, if you have the 70-200VR - why buy a 85mm?
Personally I'd spend the money on a wide angle & hold on to that D300s & keep the D90 as a backup or sell it off for yet another lens...
But that's just me....