here's my 2c, I've been playing a lot with films lately, I've gone a bit nuts and seem to have one of everything right now.

I recently inherited my dad's old rangefinder, a Petri 7s Circle-eye with 45mm f/2.8 lens. Unfortunately there was just the beginnings of moisture/fungus behind an element (probably my fault when I took it out to play with a few years ago), when I cleaned it off the coating came too (although the iq still isn't too bad). I'm keeping it for memory value only, I know I could get another decent one off ebay for $50.

I've never played with a QL17, but it looks roughly the same, leaf shutter and fixed lens. One thing that JRW touched on, I'll expand a bit.
These cameras (especially old rangefinders) are fun. They are not for fine art. If you want to make 2'x3'-sized prints, get a 5D or better.
But that's why I like these old things, I just throw one in my pocket when I'm going out for a walk and never know what I'm going to find (I suppose that's the definition of 'street').
They're quiet (at least a lot better than a film slr with motor drive), quieter than my 7D, not sure about the 5D3 silent mode, makes for great discrete street shooting. They're certainly a lot smaller, hiking would be good too.
So if you want to go out and have some fun, by all means keep the rangefinder. But if that doesn't sound like you, just do it anyway, run a film or two through it and you might discover you like it.

As for EF-mount film cameras, you can't get better price/performance than an EOS 3, mine cost me $150 or so. Has the same 45pt AF from 1D/s, but with eye-control, takes the 1D-series focussing screens (i've got an EC-cIV in mine). It does chew batteries when you don't use it, just take them out when you get home (I also bought a PB-E2 grip for it, that takes my 8 eneloops to save on batteries. It can do 8fps with that, but that's a 5-second roll of film, I ain't made of money).
It's great fun going out with just the Shorty McFortington and a yellow filter with B+W film in it. Last weekend I took one on a Bucks' party, brewery tour, I don't even remember taking half the shots being so blind drunk, but they were still perfectly in focus because of the eye-control AF (and f/4).
But unless you shoot with Efke KB25, Ilford Delta Pro 50 or Velvia RVP50 (some of the best films around today), you'll get better IQ with a 5D3. When the 5D3 came out I did the maths of how many rolls I could do for the same $4000, made my choice and got my EOS 3. I've had some great results with my Samyang 35/1.4 and Velvia 50. Probably not as good as a 5D3 (I don't have one to compare), but at least as good if not better than my 7D.

As for flash and whatnot, I'm not bothering with film. Yes, I know people used flashes for over a century before digital came out, I can just as easily put my 430EX on my 3 as my 7D, but i'm just too lazy to learn. Chimping on the LCD is the only way to go for me, otherwise it's a bit of a learning curve, expensive with film, and you don't get the direct-feedback (by the time you get the films processed a week later you'll forget what settings you used anyway). ETTL has also come a long way in the last 10 years.

JRW mentioned cheap medium format, I've also been playing with that too. I'm intrigued as to what 'current lenses' you can get for $500 (i'm presuming mamiya 645af lenses, if so that's a good deal, please elaborate!). The cheapest way in with good IQ is Pentacon Six or Kiev 60, Zeiss Jena lenses go cheap ($100-200 for even the latest Red MC lenses). Or go the Mamiya 645 (Super, Pro, ProTL are the 'sweet spot'), you can put Pentacon 6 lenses (and the more expensive Hasselblads) on it via adapter, or the mamiya 645 lenses aren't so bad either.
I've also picked up a Mamiya 645AF (which can only take old 3rd-party digital backs, not the IQ180 unfortunately) for $400, which may have been even a bit much. They can also take 'old' mamiya 645 MF lenses, plus the new AF lenses (which are damned expensive still, as much as I'd like one).
And the IQ out of them is great. I scanned a shot on Velvia 50, taken with mamiya 645AF and Zeiss Flektogon 50mm f/4 Red MC, at 2400dpi to a 21MP file, can't even see the grain and damned sharp. I could scan it to 9600dpi with a bit of tweaking my scanner driver (i've got an Epson v750-Pro, best flatbed ever made), but then i'd get an unworkable 334MP file that would just show more grain.
But for $500 worth of camera and lens, $600 worth of scanner, $20 worth of film and developing, it will still beat digitals over 5x the price.

If you're into the Lo-Fi Lomo side of things, i've done that too. Scour ebay for bulk lots of expired films, go out shooting anything and everything, and expect to go through a lot of films before you find what works (but that's half the fun, not know what it will look like until you get it back from the lab). A lot more fun than sitting on photoshop messing with colours yourself.