Rain
As far as I can tell, my best bet would be a JCM-800 - it seems to cover as much ground as I need - not too modern, not too retro, yet capable of delivering practically every type of tone I use.
 
For those of you who've kept up with the more current offerings, what would you recommend as an equivalent of/closest thing to a JCM-800 in the current line-up? I'm looking for a head + 4x12 cab config...
 
 

You need to listen for yourself with your own instrument (or something very similar). On more than one occasion, after trying things out I've come home with something completely different from what I thought would suit me best. 
 
And when trying them be aware that if you want to change sounds with a footswitch, be aware that some Marshalls (like my DSL) don't always do this so well because of vastly different voicings between the channels and shared EQ. On my DSL with the Ultra Gain channel the bottom drops out because it's voiced with the low end rolled off (something that's not uncommon in high gain preamps) compared to the Classic Gain channel.
 
 
If it has to say Marshall - and if so I certainly understand this - the current options are limited and some are quite pricey. 

I once thought I was stranded on the Marshall Islands. You can imagine my disappointment when I went backstage and saw that it was just a cardboard cutout.

UbiquitousBubba
I once thought I was stranded on the Marshall Islands. You can imagine my disappointment when I went backstage and saw that it was just a cardboard cutout.

LSHMCOMN!

The JCM-800 is the one I'm most familiar with, though I haven't had a chance to play one in, uh, 20 years or so. Obviously, the way I hear things changed dramatically since then.
 
What I know for a fact is that, with the exception of one amp (a Valvestate 2000, on which the OD channel was nasty) pretty much every Marshall I've worked with had that type of tone I'm after, w/ varying degrees of quality. But in essence, even the little MG has that.
 
I've played other amps like Fender, Vox, Boogie, Laney, which I liked for different reasons, but none of them felt home. I guess I could shop around and try things, like those EVH and such. But at the end of the day, I'd rather just go for what I know works for me.
 
One of the reasons I'd like head+cab instead of combo is that I'd like to have the option to operate the amp from my recording position and have the cab isolated/in a different room.
 
 
 
 

Rain
 
One of the reasons I'd like head+cab instead of combo is that I'd like to have the option to operate the amp from my recording position and have the cab isolated/in a different room.
 
 
 
 

I guess standing in front of the amp to have yer pant legs flappin', isn't an option??

I still don't know exactly what you want. An 800 is a really rockin' amp that can shake the rafters, but it can also deliver that low volume pre amp distortion that sounds like you're jiffy popping bees. Where in that range do you want to be? If say all of them, then you need a master volume or power scaling feature built in.
 
I find most stomp boxes sound better to me than most master volume circuits. Power scaling is a patented technology, so most amps that have it are a little pricier to cover the overhead. An other option is to get something used and abused like an old Marshall 50 watt, or a Sovtek MIG 50 and have it done up with a good quality master volume. I would likely be making the pawnshops part of my regular schedule. New stuff is new stuff, but I don't know how good a value it is.
 
You might find an old Gibson amp or a Supro, and never look back. Best sounding rock amp I've owned was a Trace Elliot Speed Twin 100, and I've owned a lot vintage 100 watt Marshall's. Who knows, maybe a Kemper is on the horizon. 

Master volume is a must. 
 
I'm hoping to be able to play reasonably loud to record guitars.
 
I pick the 800 because it's the last of the Marshall's I'm familiar with, and it's closer to what I want than the predecessors.
 
As for the successors, I really don't know them - I would expect that they offer higher and higher gain, which I don't really need. 
 
DSL is the one that seems to come back.

I have a little Class Five amp that is pretty much dimed most of the time.  I like blending it with a little Fender Pro Jr. that's on 3 and maybe a tiny bit of crunch from an OD pedal.

And after much browsing, I'm thinking that this will be the most likely candidate.
 
http://www.sweetwater.com/store/detail/DSL100MX412A
 
I'd never really shopped for head+cabs, so the price tag on this one surprised me - I wasn't expecting to find something new for such a low price. 
 
I still have to test it in person - and to wait for the budget, but, things are looking' good.

Realize that cab is NOT the current 1960a slant cab with the regular/currently used G12t-75 Celestions in it....if that matters.  That [1960] cab alone retails new for about $800...used about $350-600.  I think the MX cab is also a tad smaller in size, ..not that that really matters. 
The DSL line is Marshall's lower priced line as well.
That's why this rig is priced at a level that seems inexpensive, for what you're getting.
 
That said, it probably sounds great, but I've never played thru that rig.  That price is also much lower than finding a JCM head and the 1960 cab used.