From a personal point of view, I like to pay for half, if the decision to go out was a joint decision.
The whole opening a car door, pulling back a chair (so the woman can sit down, not from under her!!) and paying for the meal etc is a dying art but should only take place when the guy is being romantic and generally treating his wife/partner.
Although I am a very independent woman, there's a part of me that likes to be girly and feel a sense of security & protection from my fiance (and to receive the odd 'I saw this and thought of you' gift) Romance isn't dead, just out of fashion!
Giving up your seat on a bus/train? - I don't think it matters who you are, if there's someone who looks like they need the seat more than you do, then it's only good manners to do so.
Same with holding open doors. Maybe, if enough of us hold open a door for the next person, then they just might start doing it too.