K.,
My kids are (now) 17 months and 3 years (turned 3 in March). We have worked on naps in our house for a while, and this is what worked when the baby was taking two naps.
The older child gets TV time (his only TV of the day) when the baby went down for a nap. I bought Thomas and Bob the Builder because they have 10 - 15 minute episodes, so it was easy to turn off in the middle because the stories are so short.
Then, the older one would nap before the younger, so I would put the younger in his crib, and read to the older and go through the naptime routine. If the baby got fussy, sometimes the older child had to forego some of his books. Sometimes babies need their mommies. He dealt with it ok, as long as I explained he would get extra books at bedtime... sometimes we picked some out and we made a special pile for bedtime. My boys share a room, so both beds are in that space.
Then, about an hour after the 3 year old went down (he was then 2), I would nurse and rock the baby to sleep. I had to be close by, so that when the 3 year old woke up I would run in and take him out right away so he didn't wake the baby.
NOW, we are down to one nap, and it (usually) works much better than trying to schedule two naps for both kids. You can look forward to that :) They both go down for nap at the same time, and are actually both lying down now in the same room and going to sleep. (now if I could just keep my 17 month asleep without waking mid nap I'd be set - see my post earlier today!).
You might have luck with the following:
Set up a pack and play in your 3 year old's room, and let your baby play in there while you go through your nap routine with the 3 year old. Give the baby quiet toys to play with and keep the room quiet, dark, and maybe play some sleepy music. Then, when it is time for the 3 year old to lie down, take the baby quietly out of the room. My boys would both look at books for a while at 10 months, especially is there is a favorite book or subject for books. You could save those book just for that time of day, if she has some that she likes.
Maybe that will help?
Good luck!
J.