15 days on the golden route from a first timer
We did 3-3-3-5 nights, Tokyo-Kyoto-Osaka-Tokyo. Wished we'd had a bit more time in Kyoto to be honest as there was just so many beautiful places to go.
Where we stayed: in retrospect I wish we got a bit off the golden route. We did two day trips to mountain Onsen which were stunning. Next time I would stay in one. I'd love to stay near Lake Biwa as well, but didn't have the courage to plan this as I'm more comfortable in cities. But staying in the center for Osaka and Kyoto felt a bit too hectic after Tokyo. 15 days and so many gardens
Hotels: we loved our 3 star rooms. Small but reasonable, we chose hotels that offered breakfast and spa (sento) facilities and highly recommend. So many brilliant free amenities and one even had an open bar 3-8pm. 100% free booze.
Bars: We found navigating this difficult. We don't mind paying a cover charge but often you don't know how busy it will be until you enter and it's awkward to leave. Also note some bars allow smoking. These are marked on the four as a smoking area but you won't know till you get there.
Food: I don't know if we just got a bit lazy but it is so easy to eat middling fast food level quality. We did get really lucky on a few meals and maybe just needed to spend a bit more (typical budget was 4,000-5,000 yen per head for dinner). Overall we could have done better. Note many restaurants are not on tabelog, and it charges a hefty 800 yen booking fee. Lots of Japanese people we met do just use Google reviews and not tabellog contrary to reddit advice.
Shopping: we did too much of it and spent too much. Yes we got an extra suitcase and shipped this straight from Kyoto to Tokyo, asking them to hold it for 3 days while we visited Osaka. This was a brill idea and cost about 2,700 yen so well worth it. While step free access is better than most countries, rush hour makes manoeuvring huge bags a pain. Plus we probably visited uniqlo almost every day plus many konbini and department stores etc. Will tone it back next time. I would plan to shop towards the end of your trip on this basis.
People: we found people so lovely, kind and earnest. A bit of humour goes a long way. Key thing is respect and manners. And no littering. Jesus the lack of garbage bins is insane. Corrolary is incredible public toilet provision which is spotless. Do not eat on transit or in public space. Don't sit on temple steps. Don't speak loudly. And be careful about photos, many shop owners and service people don't want to be in them.