Nikky could be onto something there - I find the feed/play/sleep routine doesn't exactly work for Alex as by the time he's getting tired from playing and ready for sleep he's also hungry again (piggy-wig!) so he likes a small feed to relax/top him up before he has his nap. He then sits up on my lap for a few mins before I put him into his cot awake and he'll wriggle/chatter for a little bit before nodding off.

Mind you, he also takes a bit longer to get to tired stage - he's usually up for 45mins to an hour sometimes a bit more.