Originally Posted by Madey

Our plan is to arrive JFK, T7 at 4:00p; check bags; go through security; head to Concorde Room; enjoy dinner; board flight; enjoy a nightcap; sleep; wake in time for a full breakfast before landing.

Like cws, I'd personally say that this is way too early. CCR is nice but 2 hours there would be plenty!

[...] Is it customary to tip lounge staff (server, bartender, other)?

No

After takeoff, is there high demand for lavatory (i.e., can I spend 10 min in there changing & washing up before sleep)? Same thing for pre-landing -- i just don't want to be rude.

There is high demand and only two bathrooms for the cabin. So you can of course do as you wish but if you spend 10 minutes some people will definitely be waiting outside

Any tips or tricks we should know?

When you arrive at JFK, F counters are at the end of the hall on the left. Even if you do not check in luggage go there and the nice people will escort you to the front of the security queue.

Also, I would personally skip your plans of full breakfast. You can have it in the lounge at T3 instead, you should have enough time for this.

Thanks again in advance for your guidance!