Book any two together (D/G) if you want to talk to each other. The windows are better for singles or couples who don't want to interact. It's true the middles still require a little leaning forward but the As or Ks are you must get out of seat and stand in aisle. It's not conducive. Some couples I understand are already at the place where they want the peace. Mrs. QRC would kill me if I booked the windows front and back and therefore we always choose D/G combos when together on 35G, 35K or the long haul A333s. (maybe in 5-10 more years it will change).

As for seats. Absolutely positively do not select 11D/G, but generally you won't be allowed to anyway - they are so terrible CX generally does not release them for pax. Anything else D/G is perfectly fine. Personally I prefer forward cabin as the rear cabin occasionally gets interlopers from W and Y using the lav at door R2 separating mini cabin from main J. However, it seems some people love intimacy and privacy of mini cabin. YMMV.

The only seriously different seat arrangement is the front row of J in mini cabin (is it row 20?) in 35G. IIRC the screens are in the bulkhead and you have a bit more floorspace. Or maybe I'm remembering the 333 configs...basically it's the only D/G pair with a fundamentally different structural design due to the bulkhead. I don't love row 20 DG traveling alone or with Mrs QRC just two of us, but I do like this set of seats with our little one.

Service flow comes from forward galley (door 1) if that matters to you.

Basically if D/G, I think any seats are fine except absolutely not 11 D/G, and maybe 20 D/G you want to think carefully about. But 20 isn't flawed like 11, just different. 11 DG are so bad that if you do get stuck there you should change your flight or demand a refund.