"How do those of you with older kids organise things?" - Badly, mostly!
When Orbit was younger, I would do as you're doing, get DS1 to bed and then put Orbit down a bit later on. This was quite hard work, juggling Orbit and DS1, especially as Orbit used to like to do his feeding marathons just when DS1 was in the middle of bath and bed.
Now Orbit goes to bed at 7pm and DS1 at 7.30ish, so after tea I put DS1 in front of Cbeebies at around 6.30pm and put Orbit to bed, then come down and do DS1. This gets a bit more complicated on bath night - I used to do Orbit first and put him to bed, then start DS1's bath, but it meant Ds1 was going to bed really late, so now I do them together, which is a bit of a juggling act:
Both children into bathroom
Run bath
Orbit undressed and into bath
DS1 undresses self and into bath
Orbit out of bath
I dress Orbit in other room while Ds1 talks to me from the bathroom so I know he's not drowned
Orbit waits on bouncy chair in bathroom (normally shrieking)
DS1 out of bath (this takes a LOT of negotiation, while Orbit shrieks - very restful ) and into PJs
DS1 downstairs to watch Cbeebies while I put Orbit to bed
DS1 to bed
On the plus side, DP is upstairs right now giving Orbit a bottle of ebm, which seems to be going really well, so we might actually be able to go out next week as we planned! Just have to find a babysitter....