You might think about LH FRA-HKG, then TG HKG-BKK:
- The FCT in FRA is arguably the best lounge on the planet, at this point at least.
- HKG is a fantastic city for a stopover: great food and hotels, easy transportation within the city and to/from the airport.
- For HKG-BKK, you'll get a private ride from the immigration area to the TG lounge in HKG. On arrival, you'll be met at the plane, whisked through immigration, then sent off in a limousine to wherever you're headed in town (all courtesy of Thai).