I've just signed up to V*rgin Active, so looking forward to trying out a few of their gyms and exploring what spa facilities and showers they all have. Any tips are welcome on good branches to visit etc.
Didn't bother signing up to Nuff*eld again after their sauna and steam rooms kept being shut down (plus they closed Canary Wharf).
haven't been to Virgin Active for a good few years ... but my favourite steam rooms were:
Mayfair / Marble Arch - big dark steam room next to the showers - in the men's changing room
Kensington - usually too bright since the refurb, but sometimes fun - in the men's
Notting Hill - small, but sometimes good action - in the men's
Strand - by the swimming pool, but mostly men
Aldersgate - by the swimming pool, but sometimes action
Walbrook - in the mixed spa area, but occasionally steamy enough for action