Your dreams are definitely not pipe dreams... those are entirely possible, and indeed excellent passages..... and your dreams are very healthy ones....
All of our family holidays are now sailing ones, with trips across to France, Belgium and Holland, as well as shorter weekend journeys of a more local nature... and the family would have it no other way...
Obviously, getting the family enthusiastic is SO important.....
Picking the weather is crucial.... the Ionian will obviously help in this respect!!!!!! but when you get back, the task continues....
I have had to make a real effort to do lots of local trips to beaches when i would have preferred to go somewhere new or different, mix longer trips up with plenty of shore days, and most importantly of all, be prepared to not go sailing if the weather was less than perfect in the first season... gradually as they have become more and more keen and confident, I have stretched the 'acceptable' weather conditions, and taken on longer passages.....
Also, crucially important, get the kids jobs on the boat..... mine are in charge of seemingly minor tasks like hoisting the anchor ball, coiling the warps and fetching and replacing the sail ties. They see these are their personal fifedoms, and god help anyone that gets in their way of achieving them!
My eldest at now approaching 11 takes a mean 3 point fix with the handbearing compass, can correct for variance, and plot them on the chart.... all took time to teach her, but she adores doing it..... we find our charts with fixes pencilled on them every 10 minutes when on passage!
They are both (younger one is approaching

accomplished at recognising light patterns from chart notation, and elder can spot a light, translate its characteristics into notation and then locate it on the chart.... all this has made the passage making a real treat for her, rather than a boring experience... this year I will start her on basic course calculations.....
Regardless, like all youngsters, then get bored sometimes, so we have invested in a portable DVD player, and onboard 12V TV.... traditionalists will throw their hands in the air, but its all part of ensuring that they are happy and relaxed on board...
My wife, like many before her, was/is nervous, and I reef early to keep the boat flat (although less nowadays), make sure that she understands what we are doing, take REAL care to explain carefully what we are doing, especially when coming alongside, and UTTERLY UTTERLY important, never raise my voice when things go wrong, and always accept the blame for any mishaps.... I take her concerns seriously. I wear a lifejacket in conditions where I might not allways do so if she wants me to, such as when reefing on the coachroof on a warm day, or at night in any conditions....
I'll also 'treat' her perhaps for Christmas this year, to a distance learning package on navigation to perhaps Coastal Skipper standards.... all part of making sure she's not a passenger, but a part of the team....
Basically its about using common sense, and avoiding machismo..... there will time for rufty tufty sails later when they are all true addicts!
Bootom line though, and most important of all..... it has been a true pleasure for us as a family..... we feel that our time onboard is really high quality family time.... we find ourselves having family sing songs as we reach down the coast, and it has united us in a shared passion more than anything else we have ever done... I can't think of a better or healthier pastime for the family's happiness
Oh.... and to answer your other question..... an Oceanis would be an excellent choice..... but be warned... its got to meet everyones needs though, or it'll not work..... we both compromised on our 'ideal' boat, and found some happy middle ground....
Go for it. You'll not regret it.