That's sort of like asking for a color that goes well with beige. Most anything will do.

but what would be ideal? my mind is drawing a serious blank

what mood / sensibility / concept is each poster trying to communicate?

Bringhurst recommends Craw Clarendon.

I'm thinkin' Vegur. Maybe it's just my mood.

...Clarendon.

Robert Bringhurst recommends Haas Clarendon, rather.

You will find a match in Linotype Clarendon (designed by Hermann Eidenbenz in 1953), but better still is David Berlow's Belizio.

Cf. Serif which will work with Helvetica

BTW, it’s complement.

Helvetica, I'm jealous of your curves. -- "Serpentine"

I'd never use Vegur or any humanist sans next to Helvetica.
Mostely choosing something quite different is a better idea.

@kupfers

http://www.fontshop.com/search/?&q=helserif&x=0&y=0&sample_text=Find%20y...

I am looking for a nice face to match with Helvetica to. Finding it tough but i quite like this idea, could work well for body text. The price ain't to shabby either.

Hope this is useful.