What do you mean by 'full on career'?
Dh works full time and I am a freelancer - while the children have not all in been in school (we have 3 - 7, 5 and almost 4) it's been totally manic as I've only been able to work in the limited time that the youngest has been in nursery and the rest is in the evenings and weekends. A lot of the time I'm working more than full time hours.
At times things have been very fraught - usually when I'm to my eyes in work - but dh is generally supportive of the work I have to do and he is pretty hands on with the boys so that he has, more often than not, been looking after them on his own at weekends. He also takes a lot of time off in the school holidays so I can work (and I get my mum to come and visit for a couple of days if I'm desperate!).
However, through the stress of day to day life we do have a very happy marriage still - we always, always eat together in the evening so we catch up then, even if only for an hour because I need to go back to the office to work. We email and talk on the phone in the day.
In fact, the key thing I think is to talk - we are always having in depth discussions about how things are going, how we can make them better, what we'll do in the future etc. Also about how we are feeling about things - it can get a bit 'Oprah' sometimes but I think a lot of people just don't do this and that's a problem.
What also helps us keep our sanity is fitting in friends and social stuff - I do make quite a big effort to book in time with my friends and dh does the same. I think if we didn't do this we'd go mad. We get the odd weekend away but we are very fortunate to have parents and siblings around to babysit.
I suppose money is a major factor as well - a lot of marriages are under strain because it's an issue, I would imagine, and we are lucky that for us it's generally not. When things are tighter (I'm freelance and dh very commission based so there are times where, for whatever reason, we have a month or two where our income plummets) we tend to pull together and work out a plan.
Just flicking through the thread - I agree with much of what WWW says - as a freelancer I get quieter periods where I can recharge batteries, getting to school events is never an issue and dh can usually get to them as well, throwing money at things makes life easier (no cleaner here but we do have a gardener, have paid for ironing to be done, cars valeted etc).