Can anyone recommend a good chair to sit in while working in Logic?

Another vote for the Herman Miller. I play gtr and ordered mine without arms for around $500. The best piece of gear I have!!

I just want to say I don't like the Aeron chairs!

I find them uncomfortable and fussy. Also, they're everywhere, so there's that.

They're famous, but some of the competitors are more comfortable and easier to work with.

I recommend the HAG Capisco:

http://www.hag.no/HAGGermany.nsf/pages/hag_capisco8107

I've used a few different, from the various ikea office swivel chairs to the herman miller thing so much loved in video edit suites.

not necessarily a recommendatiom, but: currently I'm using an old piano stool in front of a plain vanilla desk. for ergonomics I've got a wireless keyboard and mouse, MBP is up on a icurve stand.
to be honest, I've found over the years that more than a bad chair, it's been manic hours of being 'in the zone' and working non-stop that has had me end up in physio or worse, in hospital (it can happen). not taking a break to walk around and stretch was what did it. so, strangely enough I think the piano stool is working out well for me. it's not actualy that comfortable, so I am constantly getting up and wandering about in between good bursts of work, without having to remind myself to do so. plus, I get to store my reference manuals and current copy of SOS inside the seat. bonus! 🙂