As you realized later, this is incorrect. Active glasses are the least common of four basic 3D systems in multiplexes today.
The most common by far is RealD, which, as others have said, uses circularly polarized glasses. The angle of your head does not affect the perceived 3D effect. With something like 75% of the market, RealD is almost certainly what you will find in your local multiplex. Here’sa theater locator. (RealD is also known as Disney 3D.)
Next is linearly polarized, as used in IMAX theaters, both the traditional 70mm film theaters, and IMAX’s new digital theaters, the majority of which are in smaller multiplex auditoriums. These create some ghosting if you don’t maintain a vertical head position. (IMAX theaters formerly used big, heavy LCD active glasses, but they were cumbersome, expensive, and AFAIK are no longer being used by any IMAX theaters.)
Least common are the Infitec narrow-band color filter system (aka Dolby 3D) and active LCD glasses, provided by a number of vendors, including XpanD.
In light of the OP’s stated condition, I’d recommend he/she avoid IMAX theaters, but almost any other kind will be okay. CalMeacham is right in theory that an angled viewing position weakens the 3D effect, but unless your head is tilted nearly to vertical, you should see the 3D effect just fine.