Enjoy 1K on UA. I think you can learn a lot by reading this thread, the UA forum in general, and some threads on the *A (Star Alliance) forum.

You look like you could hit 150K EQM with your business class travel so then you'd get another 2 SWUs. You can also earn up to 8 confirmed regional upgrades (CR1) but you have to fly UA metal to earn those (you don't have to get the SWUs). That might be another reason to consider UA over the ocean, but to/from LAX that means LAX-SFO-FRA-SFO-LAX and you'll have to decide if it's worth it to you. I think UA has the new lie flat business class seats on SFO-FRA (but double check), so that might be an advantage. You will also earn some more miles going that way.

You may travel enough to maintain 1K and also earn LH SEN status. 1 of your business class trips should get you to LH FTL status and then you'd earn 225% on business, which counts toward the 100K SEN requirement. So crediting about 2.5 roundtrips to LH should earn you SEN status (check the math in detail). A SEN card would allow you to use UA, US, and CO lounges on any domestic *A itinerary and you could still credit those domestic flights to your UA account. You only need to qualify for SEN once out of every two years and you get it for the balance of the year plus the next two years. I really like the free lounge access for domestic travel. You would then have miles in both programs so you'd have to figure out if that is to your advantage or not. If you earn a lot of miles it is helpful to have them in both UA and LH for more options to redeem. But if you don't earn a lot, you may be short of the miles in either account to redeem for what you want.

If you decide to earn status in both programs, I suggest you make a spreadsheet of your flying and allocate your planned segments to the two programs to give you enough for the status in both programs. Crediting business class segments to LH is more efficient because of the 200-225% earning. Crediting domestic coach segments to UA is more efficient, plus enough of the business class to maintain your 1K. You can change the program you credit at check-in segment by segment (just make sure each boarding pass reflects the program you want to credit for that segment). And you can use the other status card for benefits no matter which you credit (e.g. 1P/1K card for extra luggage or SEN lounge access while crediting a LH account with lower status).

As discussed in this thread, LH generally has easier availability for awards on USA-Europe but they charge fuel surcharges of $300-400 per ticket on awards, which UA does not. As a 1K you get a lot of useful perks, particularly the ability to book and cancel any award travel without change or cancellation fees (and do a lot of waitlisting on UA only awards). Sometimes you can use that to overcome UA limitations.

You may also consider whether you can work your vacation in Europe into a LAX-DEL trip by stopping in FRA and then booking awards or inexpensive paid tickets within Europe. Depending on your fare you may even be able to add some intra-Europe flights at little cost (e.g. have your stopover in AMS or LHR transiting FRA or MUC each way). That really depends on the fare rules.

Also, UA status will not help you upgrade US flights (it's supposed to help with CO flights starting sometime). So you may consider that factor in selecting your carrier for domestic flights.