I ended up going with a Siemens "Ultimate" 42/60 panel. I've had good luck with them (three panels in service for 25 years and only one breaker that went bad), and I was able to get it quickly via Amazon Prime. Breakers are available locally. I'm resisting the temptation to move the breakers from the old box to the new one due to age, but I will keep a few old ones around for emergencies.
I also like the Siemens combo breaker/SPD device. It takes up two breaker slots, but the device has two breakers built in. The good part is that if the SPD fails, it will turn off one/both of the circuits, so I will know if the SPD failed without looking at the device. I know some people will say that's a negative, but I can put a couple of low use (low importance like my attic lights) circuits on it, and add a relay-in-a-box on each circuit that can tell my Elk when the SPD has gone bad. The SPD breaker can be switched back on after the SPD failure to continue to power the circuit, but it won't provide any protection after that. The other downside to this SPD is that it doesn't have a ground connection (only one wire that goes to the neutral), and according to the documentation, the protection is diminished if the load center has a floating neutral (mine does) because the surge has to travel significantly further to dissipate. In my case, it's about 150 feet vs. 6' if it had a ground connection.
So, since I'm in the spending mood, I think I will have the electrician install a Leviton 52120 (very pricey at about $1K) at the new load center, too. It has separate neutral/ground connections, so it should provide better protection. The good thing about this device (besides looking pretty cool, and the separate neutral/ground connections), is that it is modular and comes with a lifetime warranty on the device, including "modules". So if I understand it correctly, if a big surge destroys the SPD modules inside, Leviton will replace the modules for free. There are some "exceptions", but I haven't read the fine print yet. Will do so before ordering. Most other SPD's require full replacement. At least that's how I understand this stuff.
If I had known about the new NEC AFCI requirements, I would probably have gotten the 54/70 panel. I've got 36 circuits in use on my current 20/40, and all the 20A breakers are tandem. Even the AC and oven breakers are the kinds that have two additional 20A breakers built in. It sounds like almost everything but hard-wired appliances will require AFCI protection in the future, and from what I can google, there's only one AFCI receptacle available. Leviton makes a "regular" AFCI receptacle (similar to a GFCI receptacle). They also make a "blank" AFCI device in the "receptacle form factor". So I guess depending on the box fill restrictions (and assuming code allows it), I could mount a multi-gang box above the load center (it's in a closet, so looks don't matter), fill it with AFCI blanks, and run some of the circuits that require AFCI thru that box to get AFCI protection on those circuits.
A lot has changed in the 25 years since I wired this house.
pete_c... this will probably be the kiss-of-death for the NTP server, but it's probably been the most reliable device I've had. I don't think I've ever had to even reboot it once the initial software problems were fixed.
Thanks for all of the comments.
Ira