Hi,
I've found wearing my DS to be the best way (for him) to get him to calm down and then go to sleep when we're out. He's been worn since birth and so finds it very relaxing and a "cue" to sleep or be quiet/relaxed.

Up until he was 6 mths or so I wore him in a Hug-a-Bub and since then I've been wearing him in an Ergo carrier. I find this works really well as I can BF whilst wearing him (without people knowing) and he can zone out from all the stimualtion. It also enables me to still be involved in the group instead of having to withdraw (which I have tried - and you're away for ages!).

If I don't want to wear him after he falls asleep, I can then gently lie him down on a sheepskin/rug on the floor in a quiet room. Otherwise I just keep wearing him whilst he's asleep and almost forget he's there (he's just snuggled into me - feeling secure and loved).

This may not be for you, but it's certainly worked for me, my DS and my hubby and given us a lot of freedom when going places (more-so, I've observed, than babies that consistently have to sleep in the same cot/bed). If you have relatives/friends that your baby's comfortable with, they can also wear your bubba.