It depends on where you want to go, and how you want to get there. Right now, SIN-SYD in business class (which is C in *A, as opposed to J in OW/ST) on the A380 is wide open (as another thread in this forum points out). I just got back from an award trip where I had two segments (HKG-SIN-DPS) on SQ in C, and those particular segments were very, very easy to get- I had lots of flexibility in timing, and ended up in an SQ Spacebed for a ~4 hour flight on HKG-SIN- thought it very comfortable and a nice flight (with better food, in C, than what I got in UA F on my SFO-NRT segment over to Asia).

What's going to be tricky, unless and until SQ opens up the A380/A345/77W for redemptions across the board, is longhaul out of the United States. But if you wanted to do something like use UA/OZ/NH for the longhaul segments and SQ for regional, intra-Asia segments, that's possible (and given that UA doesn't fly nonstop to SIN anyways, and will be changing gauge to an old CO Mike 738 on their HKG-SIN-HKG tag soon, I think switching to SQ on an award flight on SIN-HKG would be an excellent idea). There's also JFK-FRA-SIN and v.v. on SQ 25/26 for a while longer, which you can get as a *A award through a partner (though the seats often don't open up until close-in).