To be honest, unless you need a certain setting, the semi- auto modes generally work for most scenes. You select your prefferred speed or aperture depending on aperture or shutter prioity and let the camera meter and do the rest. This of course is general, but if you select manual and meter correctly you are deciding what the camera would decide if you go by the meter
would you trust using the autoISO in those semi automatic modes? I prefer using Shutter priority so my shutter doesn't slip below 1/200. I have found that when I have used autoISO, sometimes my pictures come out too dark so I don't typically trust it. maybe I should be using it more?
I'm not necessarily saying use auto iso, even though I find it useful in manual mode, where I select aperture and shutter speed and the auto iso adjusts to get a good exposure. You can use one of the semi-auto modes and select an iso that gets the other parameter in a ballpark you want.
Example- you are on a good day but dull day, select aperture priority of f8 because you want a good depth of field, iso 100 gives a shutter speed of say 1/100th of a second, but you are hand holding a 200mm lens and want to be at 1/200 or faster, up your iso to 200 and let the camera do the rest. Keep an eye on things as the light changes
Its easier than manual mode, which some only shoot in, but its not always necessaray, in fact I think (you know what they say about opinions

), that manual mode should only be used when you want to use a setting that is very specific. For the most part manual mode complicates things, there are those who think it's the pure way to shoot. Pure and digital photography in the same line, is a myth
Learn your semi-auto modes well, than go manual if it suits