I think that LH does a decent job on SFO/FRA if you have lie flats on the A380 (is the entire fleet done?). The SFO lounge experience isn't good (UA club) but the FRA lounges are decent. I do hate FRA transit.

Your trip will overall, be much more pleasant if you only have one connection, and that you don't have any connections in the USA. SFO is a great port of entry to the US, and has the best int'l departure terminal in the country.

Have you considered TK? Some seem to like them a lot, and you are often better off being in the front (business) cabin of a 2 cabin airline, than the mid cabin of a 3 cabin airline.