There are several internet sources for the kind of information that you are asking about.
Carl's SailCalculatorPro Sail Calculator Pro v3.53 - 2500+ boats
has a long list of makes and models with all of the numbers crunched.
PHRF ratings give some indicator of boat speed in relative seconds a mile. For example PHRF New England - Handicapping - Base Handicaps
Yachtworld.com has a lot of information on various models on the market.
As a broad generality, if well maintained, older cruising boats do tend to hold their value. If used regularly, and maintained and upgraded over time, an older boat can be a good way to go. That said, at some point the components of the boat begin to simply wear out, and many of the older designs out there give up a lot in terms of ease of handling, and or seaworthiness.
But as I look at this discussion, I really want to emphasize that I would respectfully suggest that you are going at this in way that makes things wildly more difficult for yourself. I strongly suggest that you take to the time to build skills and learn about your options rather than come here as a newcomer looking for advise and an impossibly large boat for a first boat. This is not meant as a put down. We all had to start somewhere. But starting with very large boats only makes your dream much harder and riskier.
I apologize that I wrote the following for another purpose but it addresses what I am saying in more detail:
The dream of voyaging under sail can be a powerful one. There was a period when several times a month I would receive an email from someone who is considering doing just what you are proposing. I have watched literally dozens of folks go through this. Some are successful in getting 'out there', some discover that they really enjoy sailing and find that they really have no need to 'go out there’; some have discovered that the sailing life is just not for them, and others have not even gotten past the dreaming stage.
From what I have seen, the most successful (especially when children are involved) have been the ones who have been somewhat systematic about going. There is a lot to learn before one can safely venture offshore. No one would assume that if they knew nothing about how to fly an airplane, they could buy a jet airliner take a few lessons and be able to fly around the world. I think most rational people would expect to start with a small plane and work their way up. But for some reason people assume that they can just go out and buy a big boat, take a couple lessons, read a few books, and then go safely cruising.
While there are people who literally have taken a few lessons, read a few books and went out cruising, those that were successful following that route are far more rare than those who have done some kind of apprenticeship. Learning to sail and learning to cruise involves a lot of knowledge and no matter how much you know, there will always be more to learn, but I suggest that you at least take the time to learn the basics, and that just about can’t happen if you buy ‘a big sailboat’ and move your family aboard.
I find myself saying this a lot lately but here I go again. We all come to sailing with our own specific needs, our own specific goals and our own specific capabilities. The neat thing about sailing is that we all don’t have to agree that there is only one right way to go sailing. There is no more truth in expecting that there is one universally right answer about many aspects of sailing than there is in trying to prove that vanilla ice cream is universally better than strawberry ice cream. One area of sailing for which there is no one universally right answer involves the amount of knowledge one requires to go sailing.
For some, all they need or want to know about sailing is just enough knowledge to safely leave the slip sail where they want and get back safely. There is nothing inherently wrong with that approach. Lack of knowledge will impact the level of risk, cost, comfort, and performance, but if you want to get out there with minimal knowledge it can be done. But for others, like myself, there is much more to sailing than simply developing a rudimentary knowledge of sailing basics. If you fall into that camp, it is next to impossible to learn to sail really well on a boat as large as the one in question.
While I am in no way suggesting that this makes sense for everyone, for those who really want to learn to sail well, I strongly suggest that they start out owning a used 23 to 27 foot, responsive, light-weight, tiller steered, fin keel/spade rudder (ideally fractionally rigged) sloop (or if they are athletically inclined then a dinghy.) Boats like these provide the kind of feedback that is so necessary to teach a newcomer how to really sail well. Boats like these have small enough loads on lines and the helm that you and your crew can all participate and learn together. Being able to learn and participate, the crew will be more engaged and less likely to be bored and feel kidnapped.
By sailing well, I mean understanding the nuances of boat handling and sail trim in a way that cannot be learned on a larger boat. Used small boats generally hold their values quite well so that after a year or even few years or so of learning, you should be able to get most of your money out of the small boat and move on to a bigger boat actually knowing something about which specific desirable characteristics of a boat appeal to you as an experienced sailor rather than the preferences of some stranger on some Internet discussion group. Any costs associated with buying and reselling a small boat, will be minimal when compared to repairing a big boat that gets beat up will a novice is learning to sail on too big a boat, and are way smaller than the costs incurred when an inexperienced sailor buys the boat of their dreams only to realize with experience that the boat of their dreams turns out to be a nightmare.
From the advice that you have already gotten you can tell that there will not be a consensus of opinion on how to go distance cruising. It is nearly impossible to learn to sail well on a the types of boats you are considering and without highly developed sailing skills, a boat that large is pretty dangerous offshore.
In any event, I think that you have the right idea about taking sailing lessons. If I were in your shoes, I would sit down and put together a list of all of the things that I would want to know before I set off voyaging such as:
Rules of the road
Boat husbandry, repair and maintenance
Diesel/ gas engine maintenance and repair
Heavy weather tactics
Legal restrictions on leaving and entering foreign countries
Navigation, (Piloting, Celestial, dead reckoning and electronic)
Radio operators license exam requirements
Safe and dangerous fish to eat
Once I had what I thought was a complete list, I would set up a schedule to try to develop those areas of skill that I was currently lacking. As much as possible I would try to involve all those crewmembers involved in as many of those aspects as each is capable of understanding. This process could take as little as a year, but more often takes two to three years. The process itself can be very rewarding and can build the kind of bonds that are required to be cast away on that oh-so-small island that a boat underway represents.