Trust me, even being a Senator (top tier, Gold) with Lufthansa doesn't give me any right to a bulkhead or exit row seat being preallocated. LH elites will normally get these on the day, though it is entirely open to the airport staff to allocate you there. Using the *A Gold / First Class check in will help in this regard.
You can ask for a bulkhead seat to be pre-allocated, but be warned that you may find yourself moved to accomodate families with babies, regardless of status.
If it's any comfort, this works the same in the other direction. Only UA elites are allowed to get exit rows pre-allocated on UA flights.