Is Seattle, Washington anything like Dothan, Alabama? I'm fixing to move there next month with family?

Lived in Seattle for 20 years. The communication style is far more geared towards those who are born here. I recommend you look up things like "law of jante". However honestly I've only been in Dallas Texas, Phoenix, Arizona, the furthest east I ever was from Seattle and honestly, Seattle tries to sneak attack you, play mind games with you, and its like reptiles and demons fluster the city. I think you could potentially have a culture shock here, but some people seem to flourish. Good luck. Of course, the difference is in Dallas and Phoenix the hot weather makes people more implusive I don't know why. Cold weather seems to make these people spend more time learning how to hack and spy people who didn't study computer science or people who don't have a lot of money to waste.

A few other things, passive aggressiveness, caldestine, seattle freeze, Germany, Scandiavania, cloak and dagger, could be nice to own a dictionary (or even a bible) because there are plenty of SAT words to describe Seattle  Once again, good luck.

Aside from going from a small town to a large metro area with a very diverse population, damper climate and much cooler temps, you will also notice a major cultural difference. It will take some adjusting, but people have been relocating from small towns to larger cities since before the country was founded. You will also notice the "accents" are more generic and less "Southern". (I lived in that area for several years and met people who had relocated from the Sunbelt--the person from Louisiana had a Southern accent, the people from Arizona and Texas did not.)

No, Seattle is much larger and more diverse.

No, Dothan is not like Seattle. 

Seattle is way more sophisticated and liberal compared to Dothan. Also much more diverse.

Not like it in any way. And don't use "fixing to" in Seattle. They don't understand that it's actually a very sophisticated, immediate future form that standard English doesn't have. They think it's funny. 

Only in the sense that both places use United States dollars for currency and English is the primary language.  You're in for major culture shock.

Not remotely, no. Not on size, population, education, or anything else.

Dothan has a population of about 57k, so it's much smaller than Seattle (population of 3.4 million).