Hi gdz,
Well Valencia down to Benidorm is a good area for wintering with some nice daytime temperatures (while the sun is out - it gets pretty cool when it goes back in and at night). There are loads of stopovers on here which you have access to as a subscriber eg
A couple of Aires in that area of note are the ones at
Denia and
Calpe These are both well equipped and located for lengthy stays.
As for crime Spain is no worse than many countries (including the UK!), you should be security minded that's all. Don't leave expensive stuff on display and keep your money and documents safe at all times etc etc.
With regard to travelling down through France, we've done this very many times and regard the journey as part of the trip taking time to enjoy the country and its fantastic Aires facilities enroute, again there are loads of stopovers listed on Club Motorhome to help you
Aires are great value too, on our latest trip up through France we spent about 6€ in three weeks on parking charges and nothing at all on water supplies, waste facilities and even electricity at a few of them was free!