Hm.... very interesting question.
There are a few things that I am not going to touch on such as "Why MBA" in general - I am assuming you have answered that question and addressed it and now we are just discussing the best fit.
First disclaimer is that it is really hard to do an MBA if you have 2 kids. I have 2 of my own and I can't imagine going to school at this time. Too many commitments and responsibilities.
My immediate reaction is that an Executive MBA may be a better offering for you:
1. You will fit in better in terms of your classmates and their stage in life (35+ y.o.)
2. You have management experience
3. Format is often open for doing most of the work online/remotely and then meeting once a month. Not sure if this is an option
4. Much better look on the resume than Online MBA (most don't even require GMAT)
However, the MBA is a significant investment of effort, time, and money. You are choosing to put 2 out of 3 and money is always a concern but if you are going to buy a car/couch/printer, buying something cheap makes sense if you want to upgrade later but with MBA, you can't get a second one (nobody will give you one), so it makes sense to do it right in the beginning.
I think you may want to do a bit of soul searching (try also poking around the Ask Admissions Consultants Forum) and understand what is the main driver for you to get an MBA. Online MBA's have their purpose but they are frowned upon by many. It works more as a check-mark rather than a very rewarding experience that it can be. If you need a title of MBA to get a promotion at your current job - great, then get an Online MBA. That's the right thing. If you are looking to expand beyond your role and will need connections in the future, and need to learn from you peers and looking to meet people in similar situation, you are better off with Exec MBA - you will enjoy the experience a lot more than chatting online with a bunch of 20 year olds.... just a thought. On the other hand, many mothers do have to stick with online options as that's the only choice and you will most likely find more people in your situation there than in EMBA......