4 hours in AMS
 

I have a 4 hour layover at AMS, which I understand is probably a bit too tight for leaving the airport.
I have lounge access as a star alliance gold member, but are there other interesting things to do at the airport or nearby?

Thanks!

you could have a look at the art exhibit

4 hours is a very short time to go into the city and back. I guess if you have an EU nationality and are traveling Schengen to Schengen they it may be possible to leave, take the train to Centraal - the main train station - hang out for 1 hour and then take a train back.
If you have to go through immigration in addition to security or if you are flying to the US or TLV then I would stay around the airport.
If you exit immigration there is a central hall at the airport with shops and a nice supermarket. You could buy some goodies.

If OP is travelling Schengen to Schengen, his nationality is irrelevant.
It would marginally make a difference if he has to go through immigration, but it's always a conundrum in AMS whether or not the e-gates will work and/or whether there will be a separate queue for EU nationals (and/or whether that queue will even be faster than the non-EU one)

The "non-EU line" is usable by anyone, after all it is labeled "All passports", so if that line is faster, just use it.

Of course, but it's not always easy/possible to say which one is faster until it's too late ;)
My point was that for the OPs question, his nationality is mostly irrelevant.