M.R.
Hi D. - We did the 2 to 1 nap transition 1 week before 15 months and so far, so good. I used "Healthy Sleep Habits, Happy Child" as a guide and our son is an excellent sleeper and napper. Around 14 months, he would take a nice big morning nap but then resist the afternoon nap. By the time 4pm would roll around he would be cranky and overtired. We knew it was time.
What we did was try to 'hold off' our son to a later naptime in the morning. I thought it would be really tough but it actually has been very easy. The key for my son is switching activities every 30 minutes or so and breaking our morning routine (he was like clockwork...around 9:00am he knew it was naptime and would begin to shut down). We started by leaving the house around 9:00 - went for a walk, played in the backyard, did grocery shopping, ran errands, whatever it took to introduce something new and exciting. Unbelievably it worked! We'd do lunch around 11:00 and then put him down for his nap - in the beginning around 11:30, then slowly pushed the nap back to noon. We knew we had to do this because the two nap system was no longer working for him plus he would also be moving up to the toddler room at daycare where they only do one nap a day.
I braced myself for a rough transition and just decided that I would have to be flexible and patient while we waited it out. Much to my surprise, the change has not only been SUPER easy, but now he takes a 3 - 3 1/2 hour nap when he is with us (it's about 2 - 2 1/2 hours at daycare). Initially I was (selfishly) sad that we would be losing the morning nap, but it has opened up our schedule so much that we can actually get out of the house for longers stretches at a time and we can start doing more fun things other than hanging out in the basement all the time. This hasn't affected his night time sleep at all - he still goes to bed around 6:15 - 6:30 at night and sleeps until 6:00 - 7:00 in the morning. Now, when we first started the transition he was tired and ready for bed a little earlier (5:45 - 6:00), so we put him to bed at that same time and he STILL slept until his usual morning wake time. This results in a more rested child who is better able to handle a longer wake period in the morning.
If you don't have the book, buy or borrow it. You will find helpful tips for managing the transition even if you never want your baby to cry it out (I used it more for timing of the naps, why we might need to put him to sleep earlier, etc.). Good luck to you and feel free to PM me with questions!