Welcome back! Hopefully we will have a nice summer ahead that will be great for flying too.
I would recommend the C172, it’s very easy to get in and out with two big doors, you don’t need to step onto the wing, drop through a hatch and slide over to the P1 seat and of course with the high wings it provides great visibility below for your navigation training. It really is horses for courses when it comes to the C172 and PA28 though, both are proven aeroplanes and both are excellent for training. I trained in the C152 and then joined a C172 flying group after gaining my PPL. I’ve always found the C172 to feel a little more roomy than the PA28, this might just be a perception though.
You can indeed split your training between the C172 and PA28. However, it would be best for you to get your PPL done on just one type, that way you can can divert all your resources to the training exercises at hand in a plane you are used to. You can easily checkout on the other once you have your licence. Checking out should only take a couple of hours or so.
Good luck and keep us updated. 
Last edited by CruiseAttitude; 3rd May 2013 at 14:04.