So I figured out...

[anna7602]

That DS's ideal bedtime is 7:30. I was putting him down around 9 and he would sleep until 1 or 2 am. Now he's going down at 7:30 and still sleeping until 1 or 2 am. Awesome, except: DD is out of town right now. Once she gets back, I am going to have to figure out how I put two kids on wildly different schedules to bed. 

DD and I don't even usually eat dinner until about 7 pm. She goes to bed around 9. In between, we've been playing with the baby together and reading. I also clean up the dinner dishes/the kitchen while she puts on her pajamas, brushes her teeth and organizes her book bag for school for the next day. She doesn't need me for all of that, but our apartment isn't big and she's noisy. I can't imagine DS staying asleep through everything she does leading up to her bedtime. 

Advice? DH is rarely at home for bedtime, so there's no dividing and conquering. 

[redheadk]

Have DD play with something quiet while you put DS to bed, use white noise for DS (either in his room or right outside his door if he doesn't like white noise) while DD gets ready for bed after he's asleep.

Not sure if that would work for you, but YAY for a longer stretch of sleep!

[teatimefor2]

My son, at that age, could sleep through anything. I would have her play quietly and put him down with white noise.

Hugs, I hear you on no divide and conquer. I'll be looking for tips in the months to come!

[CloudBee]

Bang around while she's still gone, and see how he sleeps. I can go in and hold DS and he won't wake. I'm always in his room after bedtime putting laundry away and packing his diaper bag for the next day.

White noise machine?

[pugz]

White noise!!

[zeewifeandmama]

What worked for us was time and white noise. He did eventually get used to the extra sounds and the white noise on full blast helped bridge the gap. It's hard, mama I feel you.

[rbp]

What is this "putting him down?" He already has a regular schedule?

[curbsideprophet]

I was also going to suggest white noise. Is their something DD can do quietly while you but him down?

We have been putting DS down early since around 2 weeks and it has worked well for us. I wish we had done it sooner with DD. Daycare is messing with his sleep now but I am hoping he goes back to sleeping longer stretches.

[loskadoodle]

How old is he?

[speckledfrog]

I think you'll be surprised by what he can sleep through. I also totally agree with getting a sound machine, if you don't already have one.

[jena]

Your dd is older, right? Like school aged? She can learn to be quiet if that's what is needed. My house is not small but sound carries very well and the older ones know they have to be quiet when dd2 is sleeping. It's a way she can be a helper if selling it to her that way is useful.

[anna7602]

He just slept 7:30-3:00. HAPPY DANCE! Thanks for all the suggestions. I am going to do whatever I have to in order to keep this up!