I will admit I did not sand my old cabinets at all - but they went into the laundry room which is not a high use area. That was about 20 years ago and they are fine. I used Zinsser 123 primer which actually says you do not have to sand. I did clean very well and the cabinets were not high gloss. I did all my trim the same way. Zinsser BIN is supposed to be even better at sticking without sanding. It does take time for both of those primers to cure. You can topcoat, but the primer can take up to a week to cure, so don't go knocking the doors around till the cure time is up.

I think if you're going to do built-ins for the bar cabinet, you really need to match your kitchen for a seamless look. Why not place a piece of furniture there, that you can take with you when you move? Maybe something like this modular piece from PB, in black? https://www.potterybarn.com/products/modular-bar-suite/?pkey=cbars-furniture&isx=0.0.1854 Or, a buffet that you can serve food on when you have company? I'd put in the effort to move the light over the dining table one or two feet to the right. Then maybe rotate your table 90 degrees?

It is likely going to cost you far more than $5,000 to change cabinets out later. It will also be a hassle after moving into a new place to rip out old ones, find new ones that fit the old boxes (if you do/can keep boxes...if you can’t, add a lot more than $5,000), what happens if there is damage to boxes or backsplash or counter during - lol, add another few thousand dollars! Add labour costs if you are hiring labour too. Soft close on drawers I would do during the build. Soft close on cabinets you can easily add yourself after closing if you want, depends how much builder is charging for that line item if worth it to you. Another factor to consider might be whether you can roll that $5,000 into mortgage or it will be cash out of pocket. If $5,000 will get you what you really want now, then go for it. But if you are going to be compromising even going with the $5,000 upgrade, stick with the “included cabinets” and save your pennies for new cabinets later on. Down the road later on. I can’t tell you if that $5,000 is really that high or not. They don’t warehouse cabinets - they order them at a certain timeline in build, but the builder would have priced out package based on their “standards” where they also usually get bulk discounts as they use them in most homes they build. Yours are a special request upgrade not factored into their pricing. If $5,000 is reasonable or unreasonable really all depends on what the quality differences are, how much cabinetry you have, etc. Cabinets are expensive. Shaker (painted MDF) were standard with my builder which was fine as it is what I wanted and am happy with their manufacturer and construction. But I added a tall pantry cabinet and that was about $2200 CAD. Soft close for drawers (I think ~20 drawers in house) was $270 CAD. Soft close on cabinets (~28 in house) was $400 CAD. It was worth it to us to have it done for close rather than do it after.

For the record, I really like what you’ve done so far with your house. I think it’s hard for posters of a certain age to understand that trends, particularly among the younger generations, is much more fluid and can’t be contained to one genre. We are far less rigid, and for us, decorating is a process, not an event, resulting in a house that is uniquely OURS. (I’m posting this from my room with a leather sectional, rustic bench, scandi-inspired wet bar, and mcm bookcase.) I agree with previous posters that hardware will make a world of difference in your cabinetry. I lean toward matte black (might be too dark, it’s hard to tell from photos) or an unlaquered brass or brushed gold, if you have that anywhere else. Switching the faucet out to something less generic of a style/finish would also help. I would look for some rugs (I tend to like a flat-weave) with a subtle pattern/texture and maybe some patterned throw pillows for the couch. A cool backsplash would help, but I think you’ll want to replace your counter (and maybe sink?) when you do it, so I would hold off for now until you decide for sure what you want. There are some decent laminates out there, even prefab ones that don’t have the built-in 4” backsplash, which would go a long way toward making your kitchen look custom.