Sircuit - they do spell it with an 'S' - started out as regular pub at street level - beers, pool tables - and cruise area upstairs - various fee schedules have been adopted over time, so I'm not sure what it costs to access particular areas.
Sircuit is decidedly more of a Pub than a club - do a web search if you want to see what they have to say about themselves.
Some nights are 'Mixed' ie Fag-Hags permitted - other nights are designated 'Men-Only'
I've not been there myself, but what I've heard is it has been the most recent gay-venue on the Str8 people "big adventure night outs" "Alternative-Lifestyle Zoo" gawk-tours. If thats not your thing, then this might not be the best place if you've only got a limited time to explore.
Despite being a SoPV, their door policy is less selective than at other nearby veneues and there is often a high oestrogen content amongst the punters.
A more 'Clubbing' vibe would be expected at the Peel (collingwood suburb) or at the GH(St Kilda).
Melbourne generally lacks a 'Scene' in terms of having a particular concentrated area with a few venues to choose from or to pop-in/pop-out.
Commercial road used to offer that experience, but that's been dead for the last half-decade, since Prahran has started positioning and presenting itself as the new "Family" inner-suburb.
The CBD is basically devoid of anything clubby. Several eating options, and a few pub/bars
Here's a rundown of a few of the better known haunts: Laird - Collingwood/Abbottsford - classic Bear lodge, also 'home base' for local Gay Rugby club, Men-only 'Heritage Listing" Peel - Collingwood - decidedly clubby, have a variance to be highly selective at the door to ensure that the 'Gay Club' experience they are presenting is actully what is available inside GH - aka 'Greyhound' - St Kilda - Art Deco Building, Very 'Glitter', clubbish, drag shows Prince of Wales - - St Kilda - strange half and half venue on ground level - band room upstairs - one side is back-packer blokey, the other side is the gay bar - easy to walk from one side to the other. Can be very quiet at times.
DnM - a pastiche reincarnation of one of the once classic Commercial Rd venues - these days reported as popular with a younger lesbian clientelle. They are having a Eurovision Party this weekend. DTs - Richmond - Corner Hotel Pub with Beer Garden - very 'local' feel, generally older punters Precillas, Heavens Door, LoveMachine - Prahran - not sure if they're even still operating - they are the remnants of the Old Commercial Rd, springing up after the main wave washed out to sea - or more likely opened up at the tail end of Commercial Rd being 'the scene' even tho the peak was already past.
Good luck finding some mischief to get into and hope the weekend treats you well!
Hope you stay dry and warm, too :-)