kdanse.ch :) Its a great school (has branches around switzerland).I don't know when they are giving classes in Geneva though.

For a complete and updated list of tango events, go to tango-sr.com (without the www) Most of the event organisers are also give classes. 

I haven’t taken any classes for a long time, but I hear lots of good about Alejandro (www.tangoargentin.ch).  Also Evaspoletto (here on glocals)  and Claudio (www.gensdetangogeneve.ch). Almatango is also OK, but they're mostly an older crowd. There are many others, but those are the ones I hear most about. Amongst general-purpose dance schools who give tango classes, there are Cours-Bravo and Kap-danse. (Not to be confused with K-danse, which I think is more Lausanne-based.)

Mad includes tango in their classes on “danses de salon”.

All the above supposes that you want Argentinian Tango. If you want the ball-room style, then you need to go to one of the “traditional” dance schools.

In the end, it’s very personal, it depends on what kind of teaching style you prefer.

Let me know if anyone (girls) need a tango partner. I'd like to start tango lessons too (beginer). :-)

Cheers,

Carlos

PS: I'll be back in Switzerland in a few days.