New speakers for a new start?

Couple thoughts 

Given that you are building from scratch, I agree vehemently in starting with speakers first.  Speakers are frequently the worst component in terms of resale  and visually the most prominent combined with being heavy, easily damaged and hard to handle.  

You mention "I love planar speakers for their speed and transparency, but the fact that I can't sit still in their minuscule sweet spot for very long, coupled with their general lack of bass probably makes them a less than ideal choice for me."

This is more of a view of one particular brand rather than all Planars.  There are others that behave very differently.  Take a look at Diptyque.  These have MUCH better bass response and overall are an exciting speaker that works quite well and have a broader sweetspot. 

For that same sort of immersive experience you could look at speakers beyond Legacy which is a nice product.  Brands to consider:

1. Borreson which is a hot at the moment is an interesting product as is.  These are tough to place in-room but if they work in your space they are amazing

2. Raidho/Scansonic which is Borreson's former company. Same issue as Borreson, hard to place but have a broader range of pricing.

3. Audiovector as it delivers a similar experience, is easier to place and is far more reasonably priced. That said, they aren't as novel as Borreson at the moment.

There are a million other speakers around that are great.  Everything from Martin Logan, Vivid, Wilson Benesch, Wilson, Magico, Rockport, Marten, etc...  You need to find ones that you want to look at and deliver the experience you want.  

Full disclosure, I am a Diptyque, Audiovector, Raidho and Wilson Benesch dealer.  I have no affiliation with any of the other brands mentioned.  

I also love the sound of electrostatics, but having massive 6 foot tall panels anywhere in my house is a definite no go.

One possibly surprising, fairly mainstream choice are Monitor Audio speakers. They are surprisingly fast in sound and are well controlled. Whereas something like B&W speakers definitely fall on the analytical and harsh side, I’ve found that the MA speakers are just on the fine line between warm and analytical in sound.

The Silver series is good. The Gold series is better. I haven’t heard their Platinum series of speakers. A friend is running his 6G Silver 500s (current MSRP of $3200 for a pair) with a Modwright preamp and Pass power amp and it sounds delightful. They seem fairly easy to drive from an amplification standpoint.The speakers have kept up with every improvement in amplification that he has made in the last several years.

https://www.stereophile.com/content/monitor-audio-silver-500-7g-loudspeaker

The sheer cost of MBLs’ makes my foray into diy Walsh drivers look like tilting windmills with a toothpick

@asvjerry I used to own a pair of Ohm Walsh - can’t remember which ones. I didn’t keep them very long but they were wonderful speakers when paired with the type of listening they were intended for. I googled Ohm Walsh and I was surprised to find out Ohm is not only very much alive but supporting their old speakers. Kudos for making your own!

’Breaking In’ is as much You as the component....👍🤞

Truer words were rarely spoken :)

I think I would lean towards speakers that handle the reproduction of octave 0 "in-house", so to speak; as opposed to subcontracting it to a pair of subs.

Now that ought to narrow down the field.

I’m not a huge fan of subs, though I have a 12" velodyne in my home theater and everyone loves it, myself included. But conceptually I feel that HT and 2-channel belong in different realms that shouldn’t intersect: different gear, separate rooms. What’s good for 2-ch isn’t good for HT, and vice versa (at least that’s how I look at it). Punchy, forward, bright, bombastic antics are OK with HT, desirable even. But even so, I set my sub’s low pass at 50 Hz which is a bit above where my front towers roll off. The idea being to let the towers do their job and let the sub shake the couch. I tried playing with higher crossover points and it was not enthused.

Now, I’m not suggesting that subwoofers may not be gracefully integrated in a high-quality 2-ch system, but I’m afraid that without active crossovers and DSP I would lack the expertise (and the patience) to do so successfully.

Then another vote for JBLs. 12 inch woofers move a lot of air. No sub needed.