19th and 20th is better for me, though I can also do the 16th June. I can't do the 26th or 27th as I'm not in London that weekend.
Like dj_intheuk, I've already been to the IMAX to see Star Trek so I think I'd prefer a normal cinema... but I'm sure my arm can be twisted ;-) One thought though - last time I looked the IMAX is ridiculously (but understandably!) booked up quite far in advance. It may be difficult to (A) get tickets, and (B) be able to sit near one another :-(
I'm quite happy with Zachary's trousers :P