Phono/preamp/amp chain. One of them tube the others SS. Which one?

Yes, 125 pounds is just too much to move around all by yourself, I wouldn't even try.
I agree it would be about double the cost of your VAC if we are talking new. If used, that would vary. Also,some equipment is almost impossible to find used. 
I would think that building separates would be following the simplicity principle, but you could look at it the other way around, sure.

If using a LOMC cartridge, my preference would be for an all-tube phono and line stage and a solid state amp, if the situation somehow was able to demand that one be solid state and the other tube.

I would not go with a solid state phono section. The thing that transistors don't do well is low level detail; IMO/IME you are better off with an SUT than you are a transistor input (better still if your all-tube phono section does not need the SUT all on its own). If you are going to loose detail, its best done by the power amplifier since if you loose it upstream, even the best amp and speaker won't make up for that loss. 

So, the choice may depend on cartridge type - tube phono with LOMC but perhaps either tube or transistor with MM. Low level detail is important.

Inna- to me, the amp-speaker relationship is symbiotic. So, choice of speaker may push you one way or the other with respect to the choice of amp. And, sometimes, the stereotypes about "tube" and "ss" sound aren’t always the result in practice. The Lamm line stage- that two chassis Reference- is a solid state audio path with a tube power supply. But, if you had to characterize its sound, you’d say "tube."
If you are just getting people’s general views, I can only speak to what I own, pretty much still as described in my profile here (which I haven’t updated in a while- a few subs and tweaks have been added since).

Whart, agree about the symbiosis. Yes, interested in general views and considerations.
Atmasphere's opinion has a lot of weight but so far he is the only one to express this particular view, though before initiating this thread intuitively I thought that tube phono should come first and then the rest if needed.