Depends what I'm shooting. With the kitten I'll be on aperture priority because he dashes around a lot, which means lots of changing light and there's no way I could keep up with the different conditions on M without losing lots of shots. There is no ideal aperture/shutter setting, it depends too much on the image you're trying to capture. You should visualize how you want to image to look, set the most important variables first and then work with what you have. 
For example, if you're photographing a river and you know you want to capture the motion, then set your shutter speed first (say, 1/10") and then the ISO and aperture settings follow from there. On the other hand, if you're doing a landscape and need lots of sharpness and a high DOF then set your aperture first (say, f/12). I highly recommend reading a book called 
Understanding Exposure if you really want to know this stuff in detail.
As for ISO, this is another reason I don't visit photography forums or discuss the hobby with gear-heads. The pixel-peepers have become so obsessed with "perfect" image quality that they forget why we do this. If I need to shoot at 1600 or 3200 ISO to get the image I want then I'll do it. You just need to know what you're doing - on high ISO settings you 
must expose to the right to save the image in post. I use (and love) Neat Image, and I've heard good things about Noise Ninja too.
		
 
Well, that might stem from film land. 
Where you don't get to just change your ISO at will. Unless you only care about a few shots and don't mind an almost entirely wasted film reel. 
That, and ISO is extremely important in image quality.
HOWEVER, what constitutes a quality image is almost entirely based on whether the parameters of the shot aptly fits the contents of the frame. 
For images with press photography in mind (think of the awesomeness that is seen in the boston.com photo stories), sharpness is almost always of the utmost importance. That's why there is so much of a distinction between an average photojournalist and a phenomenal one - knowing how to capture candid scenes, and use the appropriate settings and do it all with haste, just knowing how it will 
likely turn out, is a huge part for that career subset of photography.
Photographs simply for the artistic feeling within the frame - it's however one wants to present it. But, coming from the film world, 1600ISO is almost always a terrible grain. Grain isn't bad, it's just the wrong amount in 
most circumstances. The softer feeling can be had with better quality with faster film (hard to readily find film above 1600, have to specialty order, thus where pushing comes into play. Especially when you don't have it on hand and have a pressing desire to use a certain speed).
In the digital photography world, it seems the quality of different ISO settings is hit and miss. Some cameras have 1600ISO settings that feature a style of graininess that blows 1600ISO film out of the water. Some cameras have 800ISO looks worse than 1600ISO film !
And many cameras, going above 1600ISO things get messy. I've seen a few reviews that show some models have a fairly usable ISO range up to around 3200 - not ideal, but far more impressive than most other cameras with those settings. 
I'm definitely no snob in terms of photography, and can easily see using a digital camera in landscape photography. I just cannot justify the expensive of a Full Frame digital body at the moment. I want one, and I also demand that I get no other sensor type other than FF. And most likely a Nikon, so I can have perfect ability to swap lenses between a digital and film body. That'd be the best right there. Take photos with digital, see what works, fire away with film. Then I can play around with post processing a digital image, and if my dreams pan out correctly, process some amazing shots in the darkroom. 
Lens swap won't work if I ever pick up a camera body larger than a 35mm sensor like I really want. Likely never will because it will always be a hobby. 
I will cease being jealous of the amazing large prints from medium and large format film.