Help me to redo my wardrobe with a twist!

Not going to be too specific, just going to give you a general opinion of where I'd start. I would really look at my needs and ask myself, "what are the essential items I will get the most use out of?" It seems that a single suit will probably do, and you tend to wear business casual/smart casual. That being said, I would select a great bulk of business casual and smart casual clothes.

Five sweaters: 2 cashmere, 2 merino, 1 cotton/linen for summer.

You haven't said what you own.

This is not one for the 'Search' function - other than to establish what profession or occupation you follow and thence require clothes. One might guess that you aree not married but do you go to the opera routinely which might suggest certain clothes? How old are you? etc etc.

Not exactly the same, but I travel every week, both domestic and international.

As such, one thing that I strive for is consistency in what I pack, and the ability to mix and match without worrying too much. Broadly, here is what I would recommend the staples to be. The numbers for each of these items is entirely up to you. I am assuming you meant at least relatively business-formal clothes, given that this question is in the MC section of the forum. Not sure what you already have, but here's what I would go for:

Shirts

The vast majority of my shirts are white and blue, simply because it makes it easier to pair them with ties and jackets. Less of a hassle, and less of a problem when you've to pack and carry things around, especially if you are traveling. Consistency is the key here. Personally, I would recommend at least 5 of each, and may be throw in the odd striped blue shirt, a couple of pink/lavender/light green shirts for variety and spring. 15 in all should do nicely. I realize you're not redoing your wardrobe here, but this is what works for me.

Suits

Since you don't necessarily wear suits, I would recommend perhaps a couple -- one navy and one charcoal in mid-weight fabrics should do nicely. Personally, I've gone with the exact same fabric and cut for my suits simply because it makes it easier for me to switch things around, in case I spill coffee on one pair of suit pants. And speaking of pants, all my suits come with two pants, because they seem to get a lot more wear than the rest. Whether or not you need a DJ is entirely up to you.

Sport Coats & Blazers

A navy blazer, of course, in mid-weight, and two (one light-weight and one mid-weight) sport coats.

Pants

A couple of gray slacks, in varying shades (the lighter the better) and varying weights (fall/winter/spring), a couple of khakis (for summer). And of course, a couple of pairs of nice, dark jeans and maybe cords.

Sweaters

Personally, I would get a couple of cashmere ones in burgundy and navy, which work great for winter months, and a couple in light-weight merino in lighter colors for the cooler (but not cold) months. Since you mentioned smart casual, you could always get more sweaters and fewer suits/sport coats.

Ties & Pocket Squares

These are entirely up to you, but usually, this is where I go wild. Ties are a nice way to mix up your outfit, and a wider variety would be much, much better. But the numbers are entirely up to you, and the frequency with which you wear them. I wear one most days, I try not to look like the guy with "that" tie. I used to go wild with my ties, but SF has changed that. Personally, as long as a tie doesn't show up once every two weeks, I am happy. So, that makes it about 10-12 ties for a decent rotation, and about 5 linen and silk pocket squares.

Cuff Links/Watches/Accessories

I used to, and still do, buy more cuff links and watches than I need. But the reality is that I only use a couple of cuff links that I really like. The rest don't really get worn. So, here, simplicity may be the key. Ditto with watches. Perhaps one with dark brown strap, one with black strap, and one diver with a metal bracelet.

Shoes & Belts

I would recommend more brown and less black, since I prefer to wear less black. So, maybe a couple of oxfords or bals in brown, and one in black? With a couple of double sided belts.

And this is usually my travel wardrobe most weeks, for what it's worth.

I would like to see photos of the bags in question first before responding with suggestions.

This is too personal. It really depends on what you enjoy wearing the most. I prefer suits and would wear those more often than khaki's and sport coats. You might not. I wear a good amount of merino sweaters, which are fine for me since I'm generally always wearing them over a button up shirt.

Totally personal.

Quite honestly, I am a fan of pocket squares with multiple colors, simply because they offer more variety and "spirit", not to mention fungibility when paired with outfits.

When it comes to ties, I work in a fairly conservative environment, so my choices for the more adventurous ties are alas quite unusable. Which is fine, so I just stick with basics (navy, dark brown, and maroon/burgundy with mild patterns, and grenadine).

You may also find this thread quite useful: Simplifying a Traveling Consultant's Wardrobe. I'd asked for advice on a traveling wardrobe, and there were some great pointers there.