Thanks to a pair of schedule cancellations, my 2.5 hour layover at LHR is now a 5 hour layover. Can't do much about it because it's award travel, so I'm trying to figure out how to make the experience as pleasant as possible. I'm an AA platinum and my parents are on a AA->BA international F award, so the three of us should be allowed into the BA Club lounge. We have a 2+ hour layover on the way back where my mom is already looking forward to shopping at Harrods.

So, I figure the schedule is something like this:

Hour 1 - get from T3 to T1, get better seat assignments for LHR-LIN, get on the waiting list for the showers
Hour 2 - rotate through the showers in the club lounge, drink coffee and read the London papers
Hour 3 - ???
Hour 4 - find a nice sit-down restaurant for lunch
Hour 5 - ???

Suggestions?

My parents have been to London before and they're not terribly mobile - if I was alone I'd try to stash the luggage and go into London for a long walk.

I don't know the AA program and lounge benefits at all, but if you have access to the arrivals service in T3, then clearing immigration @ T3 and going upstairs to the lounge would be a good time killer. If its anything like the UA arrivals, there are nice shower suites and a so-so array of breakfast goodies (I'd wait to eat until BA).

If not "terribly mobile" means they can still take a leisurely walk with moving walkways for part of it, I'd then walk to T1. If its too far to walk, I don't know what kind of inter-terminal transport there is landside. With that kind of connection, however, and given how crappy it can be to take the bus T-3 T-1, and given all the time you have, I'd walk.

Myself, I wouldn't bother with splitting the time between arrivals and departures lounges - just park yourself in one place and relax. Unless, of course, you have a real yen to see every possible lounge.

You might be able to get into the new BA First lounge in T1 if it's not busy and someone is looking kindly on you. (I think it's open already; if it isn't yet it soon will be.) BA F and J lounges are both good places to kill quite a few hours with the papers, magazines and drinks on offer.

You might want to have a look at the T1 departures lounge map when planning what to do. The only "sit down restaurant" in T1 is Est Est Est which is fine although nothing wildly special.

It will take you some time to get across from T3 to T1, whether you do it airside through the Flight Connections Centre or landside after clearing immigration and customs. That'll probably account for the best part of an hour after your technical "arrival" at the gate at T3, where there are some long walks for everyone. You'll probably get called for your LHR-LIN flight about 30 minutes or so before departure, so in reality you've only got something like 3.5 hours to kill. Take a leisurely hour and a half for lunch and a gentle stroll around the shops, and you won't be bored even if you just go to T1 and do nothing else.

I've done the AA arrivals lounge before, and the BA Club lounge is good enough without having to clear immigration. I actually prefer the Club lounge to the old First lounge, but I'd be intrigued to see the new lounge.

Be aware that BA lounge food isn't as good as it once was. For breakfast at T1, expect just cereal, fruit and yogurt.