First - welcome to the Cincinnati Metropolitan area.
Second, Mason and Westchester are pretty similar from many standpoints. Mason has an EXCELLENT school district (Mason) as does Westchester (Lakota). Mason city proper has an income tax whereas Westchester (a township) does not.
Currently your home-buying (if you plan to buy) dollar will go further in WestChester as costs in Mason are pretty high due to the growth and demand to live there.
WestChester is growing quite a bit right now, there's a new mixed use development that just got approved just North of there in Liberty Township - plus the "union center" corridor that continues to grow. I don't know as much about current expansion in Mason, because I work in WestChester, so I see that every day.
Communities around WestChester/Mason that you might also want to explore:
Liberty Township abuts WestChester and has slightly cheaper housing costs. Also no income taxes.
Lebanon area (Lebanon, South Lebanon and Turtle Creek Township) are just North of Mason. A lot of expansion from Mason is going up into these areas. But they are still considerably more rural than Mason proper.
Of course if you go South towards the city from Mason there is Deerfield Township, Montgomery, etc.. which are very nice.
I moved to the area last May, and decided to build in Turtle Creek Twp (just outside of Lebanon). We shop in Mason (about 10 mins away) and work in Westchester (about 25 mintues away).
Good luck in your decisions!!
