I have flown LH and UA in First and found that UA was more comfortable. The service was better on LH but I think next time I go for comfort. I found LH seats to be hard and not cozy. As far as the first class terminal in FRA it is hard to get to if you are connecting because you aren't dropped at that terminal. No one offered to take me there either. I will say that Lufthansa First Class lounge is really nice, lots of food, service and a great atmosphere. Don't confuse this with the business class lounge which is disgusting, crowded and smokey. The HON, First class lounge is located beyond the special check point for passengers traveling to the USA. In Frankfurt when you fly to the USA, you have to go thru a second security check just before the gate area. I believe that if you are traveling in First on United you can use any LH lounge.