I was lucky enough to be awarded a one-day bursary for the SciComm Conference, and chose to attend Friday's event. It took place at a venue minutes away from King's Cross in London. I thought the layout was great - easy to find your way around and not too big.
The timing of the sessions was pretty good, we had a break for refreshments at 11:30 and lunch at 13:00. By lunchtime we had about a 15 minute delay in the start/end of the talks, but no biggie, everyone took it easy.