Thanks for your response! Just to clarify, I'm really not buying the Mac just for Civ 5. It's more that I've had a handful of PC laptops fail on me in the last 3 years, with various defects, motherboard failures, bad construction, and so on. I haven't been able to keep one running satisfactorily for more than 6 months, and I'm kinda running out of PC manufacturers to try, so that's why I'm considering making the switch. The price tag is my main concern, as well as just making the adjustment to a new environment after using PC's exclusively up to now, but I'm getting over the first concern and I'm pretty sure I can figure out the new OS etc.
Anyway, the Civ series has been my favorite bunch of games ever since I played the first one all those years ago, so if I'd be able to run Civ5 properly on the new MBP, it'd be a bonus - but it's not my only motivation.