Back in my frequent flyer days, I always wore suits; my employer vigorously suggested being client-contact-appropriate from the beginning of any work trip. There was personal benefit, though: when checking in for crowded flights, I was often upgraded to business/Raffles class without having to pay miles. Well-fitting, fully lined trousers are every bit as comfortable as yoga pants are, and when they result in seating with more space, especially on overnight flights, then you're really talking comfort.
If bra straps and underwires are digging in, it could be worth trying truly excellent quality undergarments; I'm partial to lines from vandevelde.eu for comfort, durability and fair manufacture.
Parsley's advice about layering is golden.
In my current life-phase, I've only flown a few times, and it's felt awkward not to be suit-less. I recently tried on a Tahari pantsuit in case of funeral, and your post is reminding me it would be utilitarian for flying. Maybe some variation on a suit would work for my present lifestyle.
A suit might be overkill for your needs, but it's an often overlooked option.