Like Deanna Leigh, I, with both my kids (6 yrs. and 28 months old) do NOT waiver from a REGULAR nap routine every single day. BOTH my kids still nap to this day.
Sure, there were times of developmental changes and moods, but still, there IS a concrete NAP TIME, and my kids both know it. And they do it. So now, as they have gotten older... they KNOW there is a nap time at the same time everyday, and there is less protesting about it. It is a HABIT, now. Not a "choice."
And yes, I plan my day according to their nap times. It is not a burden, believe me.
My oldest child, my daughter, was 4 years old when my son was born... and she knew, that when her brother was napping, she had to also "help" Mommy and be quiet... I would enlist her "help" and really praise her for it... she did her best. So now, the "habit" is set. And she complies. And in the afternoon after my daughter comes home from school, BOTH my kids nap. I do the SAME routine everyday. They know it like auto-pilot now.
Partly, for your oldest, he is 2 years old... and they naturally go through this. But you have to KEEP at it... reinforcing the desired goal.
My daughter is also a light sleeper... but with her brother, if HE makes noise when she is sleeping she says it's "okay" because that is her brother and it does not bother her. But with any other noise, it will bother her. So, we talked with her about it and it seemed to help her.
If your youngest wakes after 1/2 hour ready to play at night... then just leave him in the crib.. .UNLESS he is crying/screaming/in distress etc. Put toys IN his crib for "company" and to play with. Let him be.. .and see if, once he gets out his yah-yah's that maybe he will settle down by himself and go back to sleep. My son also does that sometimes.. but if we let him be, (we can hear him playing in the crib), then he will settle down by himself and then go back to sleep. He does not cry or scream for us... he is just "up" and playing.
Also, WHERE does your 2 year old nap? Hopefully not in the same room as baby? If so, have him nap in another room. Even if he has his own room, how is he then going to wake up the baby at "his" nap time? Is is just because of the noise he makes? Perhaps, in your baby's room, put some white noise to drown-out your 2 year old's noise... we have a fan on low, when my son naps. This helps. My son also likes it on when he naps. Try that.
Or, for us, we have a room that is the "quiet room" (a small living room) and a room that is their "play room." Before nap, we ALL go in the "quiet room" and THAT is where we get ready for nap and our routine (we ALWAYS get ready for nap in the SAME room)... I have found that letting my kids watch a "Little Bear" video helps to relax them. (it's a real great cute cartoon by the way & real "wholesome"), or we read a book or poem for about 15 minutes. There is a "tv off" time as well. Then we change into pajamas, change diaper, we all "kiss" good-night, then I put my son in his crib after he kisses his sister, then I close his door, then I put my daughter in her room to nap. I tell her "no talking now, nap time... quiet...Mommy will not talk either... " etc. Then they both drift off. Our complete "pre-nap" routine takes about 1/2 hour - 45 minutes... for them to deflate and unwind. Then once I KNOW they are un-wound, it's off to nap they go. My son naps/sleeps in his crib, and my daughter naps in her room (on the floor of her room, her choice), but at night, both my kids and us all sleep together in our room. We have a futon on the floor of our room. It works for us.
Another thing... when my daughter was about 2 years old and in that "phase"... it was hard to put her down for a nap... but I found, that if I "let" her "choose" WHERE to nap... then she would, and fall asleep. Often, her choice was to nap on the floor of the living room, or on the couch. So be it. She napped this way. Then, once she choose where to nap (this was part of our routine), then she would get all her blankets and stuffed toys and make a "nest" as she called it... then she would settle in, lie down, and I would sit nearby and read a magazine... I would tell her that there is "NO talking now.. it's nap time..." and that would work, and then she would slowly drift off. I would also tell her that at this time "Mommy does not play with you... but AFTER you nap, we will..." This was enough of an incentive for my daughter.
For me, I learned that the ROUTINE of it all makes a big difference. For the times when my Hubby tried in earnest to do it "his" way... it did not bode well.. and then he SAW that the kids then got off of their "good" napping habit... and then it got all messed up again. So then, I would have to re-do the undoing that my Hubby did, and get my kids back on track. So, to me, it showed me that the CONSISTENCY makes a big difference... and that way, kids KNOW what is expected of them, hence, less confusion or "bargaining."
I know it's hard and tiring. But getting 2 kids to nap, is possible. It takes repetition, and stamina, and the Mommy KEEPING to the routine... no matter what. That is what I did... and to my Husband's relief. HE thinks it's great "our" kids nap still and he's glad I kept this part of their routine intact. No matter what.
Good luck,
Susan