SMF-DEN-FRA-BER, and inbound MUC-DEN-SMF

Outbound:

DEN - Yes, United Club (since there are no Polaris Lounges in DEN)
FRA - if exiting secured area, Welcome Lounge. If staying within secured area, Business Lounge, or Senator Lounge if *G

Returning:

MUC - Yes, LH Business Lounge, or Senator Lounge if *G
DEN - Yes, United Club (if arriving on a UA flight from FRA, or *G); No (if arriving on LH flight without *G)

As for UC passes, they are only valid for United Clubs. Only need to use them if you are not eligible to use the lounge based on your class-of-service.