My recommendation is to keep your Beocenter 9500 as a starting point, and looking around at speakers as a starting point. I should start by putting in the disclaimer that I have had an ownership interest in a couple of B&O stores over the past fifteen years . . . and was also a B&O and McIntosh warranty servicer in a past life. I've personally serviced many 9500s and Pentas over the past couple of decades, and owned three pairs of Pentas (I, II, and III) at one time or another. This of course gives me decent smattering of biases, but a good chunk of direct experience I hope offsets that a bit.
First, the 9500 . . . if it's in good working order then you could spend quite a bit of money on newer stuff (including McIntosh) and IMO end up with a lateral or even a backwards move. The CD mechanism is the Philips CDM-2 with the TDA1541 DAC and SAA7220 digital filter, which is classic stuff and has an audiophile following even today. The preamp section is fairly common-practice for the era, but is very competently engineered with high quality parts and a low output impedance. All of the noisy microprocessor electronics are enclosed in a shield can with L/C or R/C filters on most every connection, something rarely found in any consumer-oriented gear. Its weak section is the power amp - B&O was already firmly down the road with active loudspeakers, and as such the amp section was put in for secondary (BeoLink) and legacy loudspeakers. The "Powerlink" output (preamp-level plus data and turn-on signals) bypasses the power-amp section completely.
As far as speakers go - you can of course connect any conventional power-amp and loudspeakers simply by using an adapter in the "Powerlink" output. But I'd recommend you take a good look at B&O's new BeoLab 18 - it's a perfect form-factor replacement, and the Acoustic Lens is ABSOLUTELY no joke - it performs exactly as claimed with an extremely even response on the horizontal axis and a fairly narrow vertical pattern. This fits perfectly with your need for good off-axis listening characteristics as well as minimizing the reflections of the hard tile floor. While I do have quite a bit of affection for the old Penta, I know EXACTLY what you mean by their "reserved, muffled" quality, and the current B&O speakers are worlds . . . no, galaxies, ahead of the Penta. Much has happened in Struer over the past thirty years.
A step up from the BeoLab 18s in the B&O line is the new BeoLab 20, which is simply an update of the BeoLab 9. I personally own a pair of 9s and absolutely love them, and while the 20s look cool and sound great, I think I still like my 9s better. Many B&O stores might be currently in a position to make good deals on their demo BeoLab 9s right now as well. You might also get a decent bit of trade-on with your Pentas if they're in good shape.
Do keep in mind that most B&O stores are HORRIBLE-sounding spaces, as it's very difficult to flatter the entire product line both visually and sonically in the square-footage that a B&O store has at its disposal. But B&O knows this and thus very strongly encourages the dealers to offer in-home demos.