We too are in the same boat!!
My almost 11 month old DD is almost ready to go to one day sleep. She will go about 3 days in a row only wanting one, then want 2 one day, then back to just one again. We're just playing it by ear at the moment....but its a bit of a struggle.
On the days she only wants one sleep she will have a "rest" in the afternoon, where she gets very tired and grumpy looking, so I put her in the cot (or pram and take her for a walk) and she will shut her eyes and look like she's about to have a sleep and then 5 minutes later you can hear her chatting away to herself in the cot! She will normally be happy on her own, chatting and laughing for about 30 min and then she calls out to me and I go and get her. She is often re-charged by then and full of beans. Its almost like she just needs a little break from her busy life!
That being said, she gets up between 5:30-6:30 and is desperate for her first sleep at 9:30. We tried stretching her until 10:30 to try and get the amount of time awake a bit more even morning and afternoon, but she didn't sleep as well in that sleep, and then would have a really disturbed night sleep. She will sleep between 1.5-2.5 hours. And she's ready for her bath and bed at 6pm.
Sorry, very long answer for a simple question...I guess what I'm trying to say is that it seems there are lots of us out there trying to sort out what to do with day sleeps, but that trying to stretch to one afternoon sleep is not necessarily going to work for everyone. We certainly couldn't do it, but seem to manage a long stretch awake in the afternoon!
PS Very glad to find this post and read everyone else's replies - always nice to know you're not the only one who had a nice routine worked out and lost it suddenly!