I tend to go more towards British spellings for those as well. Theatre just looks better, and I've seen it used for a more professional play I went to. 

In my opinion, I don't think this is really a matter of preference, because 'theatre' is used to refer to acting and plays on a stage. 'Theater' is used like a movie theater, with concessions and movies. But that's just my two cents. 

(Cheesy pun ahead:) Greyt though, Ashlee! XD I'd nearly forgotten there were two ways to spell theater, actually.

I prefer theater, because, to me, theatre looks too...er, theatrical. :P

Both words are the same(ish) colors, but the colors are in different orders. Theatre has extra reddish/purplish/maroonish in it [because of the placement of the R at the end], and theater has extra yellow/brown in it, because the E is first instead of the R. Both words invoke the color of deep red velvet stage curtains and are one of the few words that bring a picture to mind.

Interesting! I use theater, but for some reason theatre sounds more like someone would use it to describe a Shakespeare play or something.

I use theater because that is what I learned was correct. It kind of bugs me when I see words that have the r and the e backwords, because I feel like it is incorrect. Theater is filled with bright yellow colors and deep browns and golds. Theatre is more deep red with a little purple along with the other colors I said.

This goes for pretty much all Brittish words for me (spelling, not color). I write almost everyday and like you said, Ashlee,  spellcheck says Brittish words are wrong, because my Beta is set for American English.