Cineplanet sion should definitely be on your cards for catching a late night movie coupled with a dinner at the nearby Peninsula.
The theatre has good seats thought slightly expensive. Some of the front row seats on the extreme right are a strict no no as you cant even see the screen properly. Try to spend the extra buck but get a good seat somewhere at the back. But the terrace is a nice place to lounge around at the interval where you can freely smoke in the open. You normally get tickets for most shows without a hassle. Its a nice idea to arrive an hour or two hourly and buy your tickets then go to the nearest Peninsula for drinks and a exquisite multi cuisine dinner.
Car parking can get messy, go on a bike if possible. There is a handy HDFC ATM attached to the movie complex for any emergency money.
This is the only high end decent multiplex for those staying in chembur/ghatkopar apart from IMAX wadala.