I have a lot of work items tailored. Many waistbands. Occasional dress bodice. I don't do the hems myself except for casual pants or an unlined straight jacket sleeve I may whipstitch by hand.
Only items that fit generally well but would not be okay without these changes. Perfect off-the-rack fit eludes me work and dressy items.

An alteration that i will be trying out, per The Directrice blog, is opening up the bottom side seam of blouses a few inches to allow them to lie flatter and cease the bunching even a well fitted blouse is prone to. Side Vents.
Am queen of the woven button downs so this tip was of interest. Anyone else done this?
Since I thrift a lot of items, my feeling is that I can afford to tweak them without much added cost, overall. And it generally leads to a feeling of confidence when things are fitted to my actual body rather than some standardized ideal. So worth it.

I do a lot of alterations as well (hems, buttons, taking up necklines, slimming at side seams, shortening sleeves, waistbands).

I've wanted to get things altered, but the two local tailors I've seen seem more about doing specific very basic alterations - pants hemmed, buttons, etc.
if I look farther afield, what should I look for that will help identify a true tailor that will help identify the ideal alterations vs someone like my local options who does only the basics?
Or do I need to learn exactly how to identify those more nuanced alterations myself?
Thanks.

Sea-salt, I'm not sure where you live, but I'd start with reviewing yelp or asking your friends who they use, what they use them for & how satisfied they are.

In reply to sea salt, I would say that sometimes the help of a friend with a good eye can help you determine what would make a garment work better for you. With another pair of hands to lift, pin, and tuck you'd be amazed at how much it is possible to do yourself. Practice on some thrift pieces that don't matter too much and check out "how to do......." Videos on YouTube. I assume you call it YouTube over there too? There is so much info out there nowadays. I found this forum by asking "how do I get rid of coat hanger bumps?" and there you all were! Lol

I've only recently started having items altered, but now I'm sold on the practice. A few months ago I "auditioned" a couple of tailors, and found one I'm very happy with. So far my alterations have all been about making the item fit more closely and more flatteringly, especially coming in at the waist--tops and blazers (or jackets in general), side-seams and darts. And precisely because I buy almost all my clothes at clearance or thrift store prices I'm happy to spend two or three times as much on the alterations.

My favorite alteration items currently are men's silk shirts--the short-sleeved kind made with a tissue-thin but washable silk. (Do a Google images search for "Silk shirts summa" and you'll see what I mean.) I love the feel of them, but I can never find them in small, and even medium is hard to find. My new tailor took one that I looked positively lost in and made it into a slim close-fitting tunic that I absolutely love. (She had to take in the sleeves as well to make it work, but it was still affordable.)

I worry that I might be getting carried away, because now I'd really like to take every top in my closet that hangs loosely in the back and add a couple darts to it. I suppose it would be a bad idea to go for more or less the same silhouette in all my tops.