Women business clothes - what brands make the right impression?

I am dreading the type of response I may get to such a question, but I really would like to get perspective.

The original problem is that I don’t know and don’t care much about brands of clothing, shoes, accessories, etc. I don’t enjoy shopping and I don’t really notice what other people wear. I suppose if I apply myself, I could pick up that knowledge but it won’t be enjoyable and I am short on time.

The reason this is a problem now is that I am in a senior position in a big company, I am known in my field globally, have to speak at conferences, etc. That kind of public profile means I shouldn’t leave bad impression with my choice of attire – and I have started wondering whether I do.
What I have done for years is use some shortcuts by finding a few brands that I reliably like and saving myself the trouble of choosing. Dress shirts from Brooks Brothers, mock turtlenecks from Lands’ End, a couple of Tahari suits and dresses, shoes from Aerosoles (comfortable for flat feet) and that’s mostly what I go with. I should mention that I definitely like conservative look and colors in my professional life (in my personal life I am partial to Desigual and bold patterns :D ). Many women in my professional network dress more creatively and I presume way more fashionably, but I am not comfortable going bolder.

So, a month or so ago I was in a “water cooler” chat (all women as it happened, the others more junior but we have informal culture), the conversation turned to somebody we all knew and I was really flabbergasted to hear how much everybody else seems to notice and remember about when she wore when – down to the brand and cost of her shoes. I couldn’t help but think if they talk about me the same way I’ll come way short of expectations. I had always had very few shoes at a time – one pair for work, one pair of sneakers, one of formal dress shoes and a couple of sandals. A week after this conversation I went on Zappos and got myself 5 pairs of relatively expensive shoes (Pikolinos, Cole Haan, etc) and felt better about that part (and even got some positive remarks from people on one of the pairs, so I must have got something right). Now my latest worry is I need to go suit shopping, since I’ve had the same two outfits for over 7 years and my weight has shifted a bit, not in the right direction regretfully :annoyed

What I would love to hear some perspective on:
Is it your impression too that people notice a lot? Am I right to think they may be drawing negative conclusions? And is it more a matter of quality/brands or of quantity (how many different outfits you can mix and match)?
The brands that I mentioned above, any of them a definite “no”, or are they passable?
Are there particular brands for women business clothing, shoes or accessories that you would recommend as good value (as in good quality), and are also on the conservative rather than flamboyant side?

Cost is not a big issue, I have a high salary and we are not spending much, it’s more that I don’t know what choices to make without spending a ton of time on research, and without changing my general style.

Any thoughts?