I know every single travel piece about Bangkok opens with something about the heat and the humidity. There's a reason for that. It hits you the second you walk out of Suvarnabhumi airport and it does not let up. Just be prepared for it.
I stayed at NapPark Hostel on Tanao Road, about two minutes on foot from Khao San Road. It's named after a 150-year-old tamarind tree that sits in the garden out front, which sounds like a marketing line but the tree is genuinely massive and the garden underneath it is where you end up drinking Beer Chang at 10pm comparing itineraries with people from everywhere. The dorm beds are pod-style with curtains, individual lockers and reading lights. It's clean, the AC works properly, and the staff booked pretty much everything I needed for the first few days without making me feel like an idiot for asking basic questions. Bed from about £10 a night. For Bangkok in August, that's remarkable.
Khao San Road itself is an experience worth having once. I walked the length of it on my first evening and the overwhelming feeling was that I was probably about ten years too old for it. It's wall to wall twenty-one year olds in Chang vests doing shots out of buckets, which is fine, each to their own. The touts are relentless. Every twenty metres someone wants to put you in a tuk-tuk, sell you a suit, or hand you a laminated card advertising a ping pong show. You learn quickly to keep walking and make no eye contact whatsoever. The side streets running off it are a different story entirely. Quieter, better food, locals actually eating there rather than performing for tourists.
Speaking of food. I spent most of my time in Bangkok just walking and eating. No plan, no list, just stopping at whatever looked busy. Pad thai from a wok on a folding table at the side of the road, 60 baht, maybe less. A bowl of boat noodles at a place with no English menu where I pointed at what the man next to me was having. Mango sticky rice from a woman with a cart who had been in the same spot every evening according to the NapPark staff. Skewers of pork from somewhere near Wat Pho that I couldn't find again if you paid me. The rule I worked out after about day two is that the places with plastic stools and no signage are almost always better than anywhere with a laminated English menu outside.
I did most of my temple visiting in the first two days, early morning before the heat became unmanageable. Wat Pho opens at 8am and it is worth being there close to that. Entry is 300 baht, roughly £7. You need to cover your shoulders and knees so I carried a pair of lightweight trousers in my bag every day which turned out to be good general Bangkok advice anyway. The reclining Buddha is 46 metres long and when you walk into the building it takes a second for your brain to process what you're looking at. Around the base there are 108 bronze bowls and people drop coins into each one as they walk the length of it. The sound of coins hitting metal echoing around that room is one of those things that sticks with you. I feel slightly bad writing this because they are genuinely breathtaking and I don't want to be the person who says this, but by the end of day two I was fairly templed out. They start to blur into each other a bit. Go to Wat Pho, go to the Grand Palace, and if you're still hungry for more after that then great. But don't feel obliged to tick off every one on the list.
Now. The 7-Elevens. I had been told about these before I went and still wasn't prepared. There is one approximately every thirty seconds in central Bangkok and they are not like 7-Elevens anywhere else. The drinks fridges run the full length of the store and are stocked with things that don't exist at home. Iced green tea, lychee juice, strange energy drinks in cans that cost 15 baht. I had a toasted ham and cheese sandwich from one on my first full day and felt mildly embarrassed about it given I was in one of the great street food cities on earth, but it was genuinely one of the better toasties I've had anywhere. I used them as rest stops throughout the day, stepping inside for ten minutes of air conditioning before heading back out into the heat. Everyone does it. Nobody cares.
I'm writing this from a rooftop bar somewhere near the river on my last evening in Bangkok, cold beer, Wat Arun lit up across the water. I've got a night train to Chiang Mai booked for tomorrow. Four days here felt exactly right. Long enough to get your bearings and stop looking like you've just landed, not so long that you've run out of things to do. If you're starting a longer trip through Southeast Asia, Bangkok is the correct answer to where to begin.