Hey these are the show times for spiderman 3. I got the timings for only cathay cinemas.

For the one at Handy Road (beside Plaza Singapura)
11am, 11.30am, 12pm, 1430 1730 1800 1825 1900, 2100 2130 2200

Cineleisure Orchard
0930 1000 1030 1100 1130 1200 1230 1300 1330 1400 1430 1530 1600 1630 1700 1730 and every half hour interval after that.

So can do you want to watch it at town or at handy road? And i think 1400-1500 hrs should be good timeslots.