I like my GAS - it pushes creativity too; especially when it comes to old MF lenses that I adapt to my NEX body. In fact that part of my GAS is quite easy to afford.... and thankfully it keeps me from buying more L lenses.
I quite agree. I'm lucky enough not to be a professional photographer and thus to the extent I have "needs" and "essentials" they're merely want-driven and thus arguably not really needs at all. As you say, old MF lenses provide a cheap, engaging adventure, often with superb results too.
If I hadn't started using mirrorless cameras 18 months ago, it would have been rather easy:
6D or 5DIII w 16-35mm f4 + 70-300L + 100mm L + a fast 50mm (Sigma Art, I guess).
That said, if stayed with dslrs and really had to cut back, I could do quite well with merely:
SL1 + Canon 10-18 + the latest Sigma 18-250 macro - a surprisingly good combination that together costs less than just about any L lens by itself
But the more I use mirrorless bodies the more dslrs feel obsolete to me (I was using my 5DIII outside for the first time in ages yesterday and, aside from being far less useful, it felt like so much pointless ballast). But I'll keep one, if only so I can easily use my 70-300L.
Otherwise, until Canon comes up with a decent mirrorless camera I would pick:
Sony A7r w Sony/Zeiss 55 1.8 (much of the time I could probably stop right there) + a wide zoom (the impending Sony perhaps, or the Canon 16-35 f4, so I can use the lens on the 6D/5DIII) + Canon 100L + a few favorite cheap vintage fast primes (which oddly seem far less obsolete to me than dslrs)
or even, if I wanted to minimize weight/bulk
Olympus OM-D w a few Olympus & MF fast primes + Panasonic 100-300