LH upgrade instruments (miles/vouchers) are good for upgrades on SQ from C to F (excluding Suites/A380).
To upgrade one has to call LH and they have to blindly request the upgrade (similar to the long-sell). If the upgrade is successful, the only response from the system is the deduction of miles/vouchers.
I think at present, SQ has zeroed out almost all award inventory due the hick-up after the Amadeus change.
RTW tickets can now be used on Suites. On a lot of A380 flights, SQ is opening up one seat in A.
SQ is always happy to upfare a business ticket to Suites: The cheapest return in P (First/Suites) ZRH-SIN is 8.300 EUR. To upgrade a D ticket for 4.300, the pricing to upfare per leg is 2.000 EUR.