First long haul trip (USA)- what am I missing?

[WiseFinch]

Long awaited trip for DP and I is just a few days away. I am a chronic under packer as is DP- neither of us will be checking in a bag but have a cabin bag each. Never been away for longer than 2 days and never left Europe! So any ideas of things I may have missed for a long haul flight would be so so hugely appreciated!!!
It’s an active holiday (hiking, swimming etc). I’ve got a 20kg case (more than I’ve ever been allowed on budget airlines which are the only ones I’ve flown with before!).
So far I’ve got (excluding clothes shoes etc)

• Travel adaptor
• ESTA paperwork (do I need to print this off or is the email confirmation ok?!)
• little 100ml thingies to decant my liquid into
• noise cancelling headphones
• couple books
• ipad which I’ll download shows onto

Clothes I’ve got 7 days worth as that’s how long we’re going for. Couple of pairs of trainers and a pair of heels I inevitably will not wear. Just seems like I don’t have enough stuff!!!! Just me and DP- no kids. Help me, what have I missed!

No it isn’t:

Available to U.S. citizens, U.S. lawful permanent residents, Canadian B1/B2 citizen visitors and returning Visa Waiver Program travelers with approved ESTA

That’s me buying up everything I can while I’m back home! Lots of stuff in the US is cheaper or just … available generally

Travel insurance - have the out of hours number on phone along with policy number.

Passport - take photo of first few pages with your details and send to relative who isn't travelling with you. Also note the number of British Embassy near where you are travelling.

Is it obvious I've lost a passport before and had to go to the Emergency room :)

I'd also have a bit of cash for tips/parking etc.

For a walking holiday?

Proper socks
Boots (wear on plane to save packing space)
Waterproof (ditto)
Hat
Sunscreen
Insect repellent
Rucksac
Tick remover
Power bank
Swimsuit and towel (microfibre)
Nightwear
Daywear
Take Kindle / downloaded things to read rather than books?

7 days worth of clothes is rather vague. Are sure you need heels in the national parks- swap for sandals!

Coat? jumper? Waterproof? Nice outfit? Packable Backpack for days out? Toiletries? Some emergency medicines? Scissors and pen? Some snacks? Wet wipes/ tissues/ lip balm/ hairbrush bobbles? Swim wear? Bag for evenings? Travel outfit?

Aha - flying from T3 at Heathrow soon so that's good to know.

I took through a bottle of water. It was an incredibly thrilling moment after 19yrs of bloody miniatures!

Its a revelation after years of mucking about isn't it?

Likewise. It’s not a huge bag but I check it in. Your pacing sounds fine but I’d ditch the heels and take some flats just for the hotel breakfast etc. Also a fleece as PP say the aircon is feirce. Also small backpack for hikes and lots of water bottles. Altitude makes you dehydrated.

I'm taking a door wedge for hotel rooms and an insulated travel mug. I take a small bottle of washing up liquid too.