art of animation has more than just 'girl themed' rooms. they have family suites done in lion king, cars and finding nemo themes, as well as the little mermaid rooms. the family suites include one full master bedroom (queen bed) with full bathroom, and then a double sofa in the living room, and an innova double bed in the dining area, which essentially means they can sleep up to 5 or 6 people.
if it's you, your mum and your 3 kids, you could sleep 2 in the table bed, 2 on the double sofa and 2 in the queen bed in the master bedroom. there is also a second bathroom in the main living area and a kitchenette with microwave, coffee machine, fridge etc. we have booked a family suite at art of animation and found that it was only approx $50 more overall than booking 2 x rooms at pop century and the extra living space for us was a bonus in making our decision, especially when wanting to spread out or needing extra privacy/areas to relax & unwind in.
if you are doing a split stay, consider buying an annual pass if your dates are going to be more than 14 days apart, as the tickets will expire 14 days after you use the first day on your ticket, regardless of whether you have used up all the days on your ticket or not. i heard a rumour that while you can no longer add the 'no expiration option' to your ticket via the website, you may be able to request it via the WDTC or at the gate.. it usually costs approx $50 - 100 per ticket, from what i have heard (i recommend checking on this, as i've only heard rumour, not confirmation.
if you have questions that you can't get confirmed here on the DIS or via the disneyworld.com website, i strongly suggest that you use the 'contact us' feature on the disneyworld website, and send them an email with your questions, listed as bullet points or numbered. they are great at getting back to you with answers, options and clarifications, and that way, you have your answer in writing directly from a wdw customer service person, and not just some of us random disers on this board
good luck with your planning.
i also recommend the birnbaum's guide to wdw 2012/2013 guide... i found it really useful for breaking down all of the options etc to help make the decision and trip planning process much, much easier!