Thanks for all the helpful input. This is a small lab and I'm not too worried about the perception of these devices, for high precision systems people would know to use something certified and more expensive, but we make lots of custom built automated systems. In reality if I can get just the 0-5v range, or close to it, even with quite a bit of error it will be good enough for most of these sensors, many are just being used in student projects.
I realize that a decent instrumentation amp that has the correct filtering, band width tuning and protection for industrial use is quite an undertaking, but we can buy those. I've designed a quick and dirty circuit using an AD620 which works, but I figured even for $20 I could probably come up with something more reliable if I talk to some people who know what to consider with analog.
To answer specific questions,
1. Is differential output important?
The sensors we need these for all use Wheatstone bridges, I'm not sure if there is any other way to read them
2. Is filtering/ bandwidth limiting required?
The load cells, strain gauges and magnetic sensors I'm dealing with are all fairly low frequency, even a cut-off above 100 Hz would probably be good.
3. The 0-10 and the 0-12 will cost you with only a 12 V supply. You could purchase a small low-ppwer DC-DC converter per board to get a +-15 V supply rather than designing one.
The switching supply will add noise.
Really, a 0-5v output will cover most of the devices, so I think I'll stick to that to keep it simple.
4. The AD524 or 624 are very nice chips.
I'll look at them,
5. You might be able to get away with a few jumpers/trimmers and fixed resistors to accommodate what you need.
Possibly, I think most of these will be embedded, so just putting in the resistors to set it is ok with me.
6, As with all IA's, you have to have a bias return path.
I don't know what that means.
7. Also look at Analog Devices AMP01 and AMP02 IA's.
These are interesting, most diagrams I see have a lot of support components, would these work as easily as the data sheet makes it look?
8. You may need a) an IA for the input, a filter and a differential output
I hope it's not that complicated, but maybe, I would like to just have one chip with a few support components.
9. Is isolation important?
Usually no, none of these are attached to people and if the are near an inductive load that can be separate. In my uses they are usually battery powered.
10. DIN rail or waterproof/water resistant boxes?
This also depends on the use, some of our machines have big metal instrumentation canisters with O-ring end caps, sometimes we just dip parts in sealer.
11. How would you do calibration?
Since most of the devices are custom, that would depend on the design it's being used in, they might just program it into the device, in the case of a feeler I'm working on that uses a magnetic range sensor I will probably make a routine that calibrates it at the full forward and back position.
12. Computation of error budget and temperature effects.