Hilton Airport - avoid.
Hilton Grosvenor - a good deal cheaper than the the Caley, a 10 minute walk from town, with three excellent indian restaurants close by. Also, very close to Haymarket Station. Many of the rooms have been refurbished to quite a good standard, but there's still the risk of getting lobbed into the hell that are the club rooms over the road (and there is the strange odour that permeates the Haymarket area some days).
Hilton Caledonian - expensive, but home when I'm in Edinburgh (due a project manager striking a startlingly good deal). Castle view rooms can be very large and wonderful. Excellent corridors and a wonderful staircase to swan down in a diva like manner. Stunning collection of whiskies. Close to Rebus's local, the Oxford Bar, and well positioned for Grassmarket and the like.
I agree with Nick about the public transport. Most mornings I take the bus out to our office for a £1 rather than the £15 it would cost in a cab. Only downside is that the Lothian Buses drivers seem to have been trained (or perhaps recruited for) very heavy feet on either accelerator or brake.
Paul
We can get better, because we're not dead yet