I have been thinking about this for nearly 3 months, pros, contras, etc and I have so many mixed feelings about both that I really need a bit of input to sort my mind... the options are the following:
A. Do a PhD and have more time for DS.
The facts: I have wanted to do this since many years ago, and now I am in a position were I can pay fees and nursery without a "significant" problem. I can work during mornings and nights and still have a several hours with DS while he is awake.
The advantages: I would have the flexibility to travel with DH (he spends a great amount of time in business trips) before DS starts school. I love the subject (history), and most important of all I would get to see DS more during the weekdays. In a way the PhD is like a hobby while being a SAHM. (Yeah, I know, don't worry I know what I am getting in... I have survived DH's and many other friends' thesis, so I know the amount of work it takes).
Disadvantages: just one salary; and here's why the thing is like a hobby... It wouldn't give me a better job or better salary, and oportunities to be a practicing historian would be rather limited as with DH's job and DS, I am not in a position to consider relocation. If I decide to go back to work later in my former career it will be very much as starting from zero, as trends and changes in software have and can make my style and skills completely obsolete in a few years time, besides... it is a profesion of the young, for some strange reason you don't see many middle aged graphic designers.
B. Go back to work and forget about the PhD.
Facts: I love the creativity involved in my profession (design)
Advantages: I'm still in time to go back without much damage, and I'm sure I would enjoy the work
Disadvantages: I would be seeing DS only 1.5 hrs per day (last holidays I realised how little I know him, I'm used to see him just after a full day in nursery when he is tired and not at his best). There's no such a thing as part time graphic designer (you end up working full time for half of the salary, the client can't wait). I don't expect that a new oportunity for a PhD could be repeated in the future.
So what would you do A or B?