for starters, i suggest you look into this weekend's "naughty by nature" event at the goose & duck ranch. although the chances of me attending are close to zero --in the unlikely event i don't bust out of town on friday, the fact that my boss is going to the party severely limits my interest-- everyone i've talked to thinks it's going to be pretty good.
building on the g&d ranch theme, there's a lot to see and do within 2-3 hours north (east/west) of the city. the air is better out there, plus they have things like lakes and mountains.... and, of course, spas.
as for plans that involve taking to the air/rails, qingdao and dalian are the most obvious, but i would also encourage you to check out the northeast. if you do it right, you can even catch a glimpse of north korea in action.
before closing, keep in mind, that 90% of the country is within a stone's throw of beijing insofar as air travel is concerned so you needn't limit yourself to points that are geographically close.