Which Sydney lounge should I use when I fly UA business class to San Francisco?

Which Sydney lounge should I use when I fly UA business class to San Francisco? As I'm flying into SYD on VA I can get into the domestic VA lounge with my VA platinum card (on-arrival access). Should I stay there of go to the international Air NZ or SQ lounge? United said I could go to either of those two international lounges.

Go to the SQ lounge.

Will I be allowed entry into the SQ lounge? United via email said I would but I've heard otherwise. 

Try. Worst thing that can happen is they say no.

You can get into the new Singapore lounge so long as you know your rights, and print out the page on the Star Alliance lounge access rules which say so.

The new SQ lounge is quite nice on the business side: all the pictures on Ausbt are from First, but there are some good pictures from the Singapore Airlines Silverkris business class side here: 

http://loungeindex.com/Oceania/Australia/SYD/Singapore%20Airlines%20Silver%20Kris%20Business%20Lounge/index.htm

The OP doesn't mention having star gold status, so I'm not sure it'll work (and even then I wouldn't count on it, SQ are notorious for disobeying Star Alliance lounge access rules because, hey, it's not like Star Alliance is gonna kick 'em out)...

Personally I'd rather have a relaxing time in the NZ lounge than have an argument with a SQ lounge dragon, but hey, some people have a higher tolerance for these things than I.

Just printed it. Ta lorks and watson374.  Will give it a go and report back on Monday

SUCCESS. At check-in the agent asked if we knew the way to the AirNZ lounge. We said we'd prefer to use the SQ lounge and she said "OK. I'll call ahead to let the SQ lounge know you're on your way". Easy as. Great view. Good food selection and 8.4 Mbps wifi