Wow! So much response! You all are a generous bunch, thank you!
To respond to some of your points:
"Out of shape and sedentary", I'm 5'8", 25 extra pounds of fat and very much lacking muscles. I used to stay fit and strong with jogging, pilates and yoga. But a combination of factors lead me to let go of good habits and take on some bad. This is turning around quickly though. I don't have any injury or prohibitive conditions outside of being weak and soft from lack of exercise.
The measured advice of Machka - Yep, I could tell she knows her stuff by her first reply. And I walked right out the door with the dogs on a 3.5 mile walk after her second reply with advice of morning/evening walks bookending a ride.
Bike fit - I have a 26" schwinn cruiser from walmart (please be kind, it was a gift). Earlier this spring I rode it to the bike shop near my house and had them raise the seat as high as it would go and add head/tail lights, and baskets so I could grocery shop with it. I asked the owner if this bike was the right size for me and he said it was not too small but the next time I buy a bike I should test drive a longer bike since I have a long torso & arms. After he raised and corrected the tilt on my seat it felt a million times better and that's when I started to really use the bike. It had felt awful prior to those adjustments. It has 7 gears. So far I have only used as high as 4. I hangout in the 2-3 range mostly.
Riding for enjoyment: Yes! This is my goal. I want this trip to be enjoyable, that is the point. Even in my daily riding I put a small portable speaker in my basket and listen to music and much of my ride is leisurely, it's just at my lousy fitness level it doesn't take much to elevate it from leisurely to challenging during some parts where there is an incline or wind, etc. Yesterday I didn't preplan my route, I just rode until it felt right to stop, listening to my body. I routed it after I got home to see how far I had gone. Yesterday was a bit windy and I had some goods from the drug store in my basket for most of the ride.
I was thinking a good goal would be riding to my old work to visit old coworkers, this is roughly a 10 mile ride and I think of it as my first milestone. Knowing that after I arrive I can get someone to throw my bike in their truck and give me a ride back home if I don't feel up to the 10 mile return is a good trick for my mind and makes it less intimidating.
Daily schedule of trip: Yes, we plan on stopping for breaks or when we see something interesting, and for lunch. And hopefully have some steam left to explore town before/after dinner. So the "half tank left" after the ride is ideal. I will post a link to the tour but first I have to explain that i accidentally lied! I just looked at the daily distances again and it is not 30-40 miles, it is actually 25-32 miles! That was an accident. I've browsed so many different tours that I got it mixed up. Anyhow,
here it is, it's on a path called the Parenzana in Istria, some of you probably know it.
Thank you all so much for assuring me this is within my reach. I am going to book the trip this afternoon! You all have made my day, thank you for the warm welcome!