16 months and still waiting.....
DD slept 11 hours solid at night from 10 weeks. Has done so ever since and is now 3.
We've had sleep issues with DS since he was really little.
I've done nothing different with DS so I'm now a very firm believer that it just comes down different temperaments.
DS has also gone through cycles but I wouldn't call the better ones of those "good sleeping" - he's never been a "good" sleeper LOL - I'd call his cycles average, bad and really really horrendous .

He's getting molars at the moment and wanting to start the day at 4.30 - I don't cop this anymore he has to stay in his cot, I don't care if he sleeps or not. When he was littler I would've either got him up or put him bed with me if I thought he might go back to sleep. Now he's older and noisier (!) he wakes up DD and I cannot cope with the two of them up from 4.30am now that DD doesn't sleep in the daytime. So I've put my foot down with him on this lately.
Sorry that was a bit of ramble lol.