When in full-on conference mode I find it's always best to be as actually engaged with real people as much as possible. One of the reasons to attend conferences is to spend time with colleagues. It's OK to not tweet every great thing your lunch companions say.
That said, there are some ways to use technology to help get the most out of conferences and other events.
Mindmap on the iPad
I take notes in mindmap format. You might have done these in school as concept maps. Basically, you write a word, circle it, and then draw a line connecting it to other words. The end result is a list of all important concepts in a presentation and how they relate ...