If it helps, let them know that I didn't get the whole internet meet thing either. ; The first time I 'went' to Mousefest and officially met some of these folks, I was pretty much going up to Disney at that time anyway. ; I figured I could melt into the back of a few of the gatherings, and see how I liked it, and if I didn't, I could just fade back into the crowd and do my thing.
Ends up I liked it - low key, friendly, not too heavy on the 'star-trek-convention-attendee' obsession levels. ; It's really just a group of people going on a Disney vacation, and while up there, planning a few chances to get together. ; You can immerse as much or as little as you want.
I'm still somewhat an independent type myself - I don't do the 24-hour hangout type thing. ; I prefer to meet up at a few gatherings a day, maybe a dinner or event night, and throw in a few hours here and there to do my own thing (or family & friends thing, if I'm there with them). ; I've never really had family or friends mind me going off for a few hours and meeting up later...I guess it depends on the family dynamic. ; With kids, it might be harder to explain!
Heck - if you make it a family trip to Disney, and then just break away for a few meetups here and there, I can't see them minding too much...and many of the photo walks and such are informal and fun enough that they could always come along.