I'd be in favour of having at least a GMT style option, and probably just GMT style - on the one hand, it's more trouble for users who don't already know their time relative to GMT, but on the other, it's accurate without the need for lengthy lists of every possible city, and without someone at DW having to figure out every possible timezone in each region, which can, as ursamajor pointed out, be tricky. (As a minor aside, from my personal POV, I'm not always working on the time zone of the place I physically am, and it seems somehow weird to set things to a place I'm not, whereas it wouldn't be at all weird to set it to GMT + an appropriate number.)