A big conference such as the ACM CHI is big is really worth attending and every movement, for me at least, is really enjoyable. A smaller preferred conference is perhaps the BCS HCI which is really good!
The BCS HCI Conference will be in Southport next year - hosted by UCLan - it should be a good event (quick plug as one of the chairs) - the call will be going out in the next few weeks as well as the website going live - submission will be next year - there are normally around 120-150 people who attend the main event and others who just attend the workshops. I hope you consider submitting your work
There is also AVI 2014, Advanced Visual Interfaces. It is usually hosted in Italy but in the past it has had some good papers published in it. This year it will be in Como.
and yes, it is small enough to have real discussions after each contribution, so, unless you are totally shy, you will know really your colleagues after the 3 days and have both taught and learned from each.
I haven't seen the AMCIS one Adel, thanks. I think that this is why ResearchGate is so useful, it lets you find out loads of things from other people in the same field, all over the world.