My first suggestion would be to get meal times (all three) and bath time down to roughly a set time each day.
At our house we have breakfast at about 6.30 when we all get up. Lunch is probably the most variable but usually that is around 12.30. We eat dinner at 6. Bathtime is around 5pm.
It sounds boring (and it was a rude shock to us after years of being childless and eating whenever we felt like it - or not at all if we didn't feel like it LOL). But it's really, really important that toddlers know what to expect every day.
Dinner is over by 6.30, which is when DD goes into the loungeroom and lies on her "Dora couch" and drinks her milk while I feed DS and daddy cleans up. Then it's bedtime. She knows this and most nights finishes her milk, starts kissing everyone goodnight and is pretty much telling US when it's bedtime. Both kids are in bed by 7pm, every single night LOL.
I know this doesn't work for some people - if you're out in the late afternoon or at night alot obviously it definitely won't work.
But we try to organise things so that 95% of the time we are home in the afternoon/early evening and find that having the kids in a good routine isn't restricting - it saves our sanity.
I'd seriously go crazy if I had both of them up until all hours at night, I freely admit I couldn't cope!