Ok, rangefinder setup specifically for 28/2 and 20/2.8

http://www.voigtlaender.de/cms/voigtlaender/voigtlaender_cms.nsf/id/pa_asan6m4e2e.html

There you will find two 21mm lenses. And Bessa L body. That would be relatively fine wide angle setup...

There's the Voigtlander Bessa R4A/M, made for wides. http://www.robertwhite.co.uk/product.asp?P_ID=1670&PT_ID=290&P=Voigtlander-Bessa-R4M-Body- with 21, 25, 28, 35 and 50mm framelines.

Has anyone recommended the Rokkor 28mm, f/2.8? Great little lens if you can find one without the dots - and even with the dots I'm told it shoots like a dream (no issues from them except it's disturbing to look at them).

I shoot mine on a Minolta CLE and a three lug M5, which both have a 28mm frame. You'd have to get a finder for your 20mm, but you would on nearly any camera. The CLE is, while not delicate, not as sturdy as a Leica - but I'm told the Cosinas are less so. The M5 is an absolute tank, nigh indestructable and easily my favorite RF.

Good luck on whatever you choose.

Jeff M