I need to fly FRA-SIN r/t leaving Sat Sep 29, returning Wed Oct 3, 2012. Since LH and SQ fly A380s this route daily that implies great demand. Are they usually full?

Any experiences on using a UA SWU for a Y->C upgrade on LH?

Not sure I can afford a Y/B fare on SQ for a *A Upgrade, but would that be more likely than an SWU upgrade on LH?

Also, I'll be getting to FRA from ATH. Can I get on the LH grading list from ATH, or should I try to get to FRA early?

From FRA I head back to ORD, (SIN-ORD wasn't a low cost option from my corporate booking site) either on LH or UA. Any other thoughts or advice? Thanks in advance.