My D70s is feeling dated. I know I can still learn lots from it, but I want a new toy. However, one of the biggest drawbacks of an SLR is the size. I think I may learn more if I ALWAYS have a camera with me. In this case, the S90 wins big cause it's being hailed as one of the best quality P&S with decent ISO and speed (f2).
Would you save money for a D300s or D700, or get an S90?
My current setup:
D70s
SB-600
-11-16mm f2.8
-18-70mm f3.5-5.6
-35mm f2
-50mm f1.8
-11-16mm f2.8
-85mm f1.8
90% of the time, I keep the camera in my bag/car with a 35mm and no flash. But it's not always with me. The iPhone 3Gs has a decent camera, but it's still behind a middling P&S, and lacks adjustment, ISO power, etc. I was considering 70-200 f2.8 or 17-55 f2.8 if I were to get another lens.
I work in a camera store so I play with these all day. The S90 is cool, but it's no DSLR replacement! The D70/D70s is really not that great, by today's standards; get yourself a D90 body for $900 tops. You don't need a D300/D300s at all... it's just a bigger, heavier camera which only makes sense if you're exclusively using it with weather-proof lenses like the 18-200 DX or 70-200 2.8 VR, etc. But with the lenses you have there is no sense to the D300/300s/700... the D90 is a *fabulous* camera, you will *love* it. It's a HUGE upgrade from the D70.
And then you'll have enough $$ left over to buy an S90 also. Because you can't NOT have a point-and-shoot. I am playing with an S90 right now and they're pretty nice. Look, it's still a point-and-shoot camera... the noise is about one stop better (if that) compared with my old Canon Elph SD890IS from two years ago. It's got a nice wide lens, and can shoot RAW, and stuff, but the sensor is TINY and the lens is TINY and just does not have the optical quality of an SLR. It will kick an iPhone's butt into the next galaxy though, and that is the whole point!
Here's what I have:
Canon PowerShot Elph SD890is (5x zoom, 10 MP)
-- Take to parties, dinner, night on the town, when my band plays gigs, etc
-- Take when I go out shooting, so my GF has a camera to use ;p
Olympus E-P1 w/14-42 ED, usually use with Nikkor non-AI 50mm f1.4 (MF only), or Zuiko Digital 40-150 ED w/FT->MFT adapter
-- Take to more important/upscale parties, Blazer games (NBA), daytrips where I don't want the bulk of the SLR but still the quality.
Olympus E-3 w/12-60 ED f2.8-4, 50-200 f2.8-3.5
-- Take when I go out _shooting_ or on jobs
OM Zuiko MF-only primes (use with adapters): 28mm f2.8, 50mm f3.5 Macro
Nikkor MF-only primes (use with adapters): 500mm f8 Mirror, 50mm f1.4, 35mm f2.8
Point being. Get a D90 and an S90. It rhymes, numerically. So it must have been meant to be for you.