Warning, A lot of text will follow that might not have all that much to do with the topic Starter's question but is more to ease my own doubts. And therefore a bit aimed at msmoto
Actually, the 35/85 combination is such an excellent match, maybe only exceeded by a 24 or 28/85 combination. Again, what one really needs to understand is exactly what one wants to photograph and the personal preference for doing this. The 24mm can be used to shoot portraits, although one must exercise a great deal of judgement in composition.
Ah no, Now you make me (slightly) doubt my decision.
After trying to decide between the 85 1.8G and 105 2.8G VR Micro for a long time,
I recently ordered the 50mm 1.8G and 105mm 2.8G VR Micro to add to the 35 1.8G I already got for use on my Nikon D5100 (18-55 kit-lens was replaced with the 35mm)
I ordered these when a local store had a sale (Tax-Free Shopping, Takes 15,97% off the list price) So I got the 50mm 1.8G for €150,- (Normally €179,- or more) and the 105 2.8G VR Micro for about €640,- (€759,- or more) Thinking they'd be a great addition to what I already had (the 35) and give me more reach and usability(VR/Macro) VS the 85 1.8 which I initially wanted to get.
Though it's too late to get the 85 1.8G with that discount, I could still cancel the 50 and 105 and get my money back.
But as I said, I decided on these two lenses to go along with the 35mm for a reason and shouldn't change my mind now because I read something I already know: The 85 1.8G is a great lens.
But so are the 50 1.8G and 105 2.8G. Right?
Besides, This discount will come again (usually twice a year.) So I could (and probably will) buy the 85mm 1.8G then. (Together with a new camera D7000/7100 or D600.)
Unless I really don't like the 105 Micro, Which I'd then be able to sell within 6 months and not lose any money on it due to the discount I had with my purchase.
Totally forgot to mention: The reason I got the 50mm 1.8 together with the 105 2.8 Micro is because I wanted something in between the 35 and 105 that wasn't too expensive and the 50 1.8 only cost me the savings I had on the 105.
Even though 50/55mm was something I rarely used when I was using the 18-55 VR to find out if I wanted the 35 or 50mm f1.8, It's so darn cheap and better suited for portraits (And probably general outside(forrest) photography.) I decided on getting it anyway.
Maybe you can do an experiment. Take your 18-200, zoom to 85mm and tape the zoom, so it is "fixed" at 85mm. Then walk around and shoot a bunch of photos, family, neighbors family, etc., and see how it works. Then, adjust it to 105mm, do the same thing. It is important to tape it at the zoom you want, so as to force you to work with this "fixed" focal length. Incidentally, use either a painters masking tape or gaffer's tape, not duct tape or regular masking tape which could offset the adhesive to your lens.
The above will help you to understand the limitations of a specific fixed focal length. It may help you to avoid buying something you later decide you do not want.
Now here's a thing I'd like to admit, The mistake I made in getting the D5100 with the 18-55 VR. While it's a great lens (depending on your expectations.) in my case it didn't offer much as a 'find out what you need/want' lens.
I should have gotten myself the D5100 18-105 VR kit, But whilest on the subject why not make that: I shouldn't have been so tight with my money and gotten the D7000 18-105 VR kit to start with.
Anyway, I got a call yesterday, My 50 1.8G and 105 2.8G VR Micro have arrived and I'll go and pick them up tomorrow. (Depending on when you read this and what your time zone is, Tomorrow could be today.)