Newborn easier ime. I just moved DS2 around with me while more or less carrying on DS1's routine. DS2 slept through most of it, being moved from floor to mat to floor to bed as we went round the house no problem. Tiny babies are very portable.
DS2 is coming up 4 months now. I bath him first then leave him on the changing mat kicking away while I bath DS1, after removing DS2's bath support and putting DS1's bathmat in. I could probably put them in together now DS2 is a bit bigger, but it works pretty well how we do it.
DS2 is happy as long as he can hear and see me and hear DS1 in the bath. He does have a dummy which I would recommend - he will only take it when he is overtired and is grizzly for that reason, but it's useful to have that option.
DS1 goes to bed first, at around 7.30. DS2 currently feeds at 4.45 so isn't then ready for another feed til about 7.45 - 8ish, so he is obviously up a bit longer for that reason, although in bed straightaway afterwards. Again that works well for us.
It's all a bit daunting but you'll find a way that works for you. I found that I was assuming the logistics of managing two, especially at bathtime, would be so difficult and horrendous, but actually we've found what works and it's a lot easier than I thought. The most challenging thing about two I found was the physical exhaustion, especially at the beginning with the overnight with the new baby. With one baby it's hard work, but at least once baby is asleep you can in theory at least sit down. With two, if it's not one of them needing bouncing/feeding, it's the other one needing a story read, playing, tea made for him or whatever, so there's not much respite at all, and when there's a bit of respite from the children housework and other jobs need doing. I'm also running my own business so am squeezing work in as well!
Things get better as newborn starts going to bed properly during the evening, I now have from 8.30 in the evening free for dinner, work and time with DH. I'm also fine from the exhaustion point of view because we are very lucky in that DS2 slept through from 10 weeks. Obviously that might not happen for you, but the point I'm making is that it does get better, usually fairly quickly, and you'll muddle through until you find a routine that works for you.