Hopefully the arrivals lounge will be open long enough to accommodate the later flights from the West Coast. My pet peeve with many of these arrival lounges (not just UA) is that they close at 1pm which is too late for some long distance flights. I guess the theory is that you can simply checkin to your hotel at that hour, but I've found that's hit or miss, and not particularly efficient if your intent was to go straight to your office or a meeting.

I visited the old T1 arrivals lounge at LHR a couple of years ago - the food offerings were mediocre (like the departure lounge) and I found it cramped. Optimtically speaking the new one has to be an improvement, particularly if they add more fresh food beyond carb-laden sorry looking pastries.