So you hit one of my pet peeves, Brentwood, where is that. People deal with info and assume some one in New Zealand or England or Alaska know what the person is talking about, but to the person it is clear - "Brentwood, you know, Brentwood, everyone knows where it is." I googled it assuming it is in the States, which it apparently is, but also in Burnaby BC, just saying. I don't mean this in a heavy handed way, but the reason I googled it was to add some contectuality to my advise.
First I agree, don't settle on what you think you might need, but start your journey into boating now. If you live in the Brentwood in Washington DC then go get yourself 28 - 30 express cruiser or trawler and start the adventure now. You will find much to learn, from the ever fun anchor discussions, gas versus diesel, etc but none of the information is difficult to learn, there's just so much of it. Two burner stove or three or four burner stove, propane to run your stove or all electric. If all electric how are you going to get your power, shore only, gen set, fuel cell, solar, wind turbine, water turbine, and the list goes on and on and on.
The boat you purchase now will help inform you on what is important later, is a trawler too slow, do you want something faster, can your wallet or your brain handle the economics of a faster large boat. If you are considering 65 feet and metaphorically speaking want to follow along the lines of the Fleming Venture, and if so do you really want to do much boating in open water, away from the coast, thinking larger rolling waves, storms to put the fear of god into you, and basically the same view for days at end?
You think you know the answers to the above questions but experience will modify your vision. So focus on the experience you can begin to acquire now. But if you enjoy the lifestyle, you will thoroughly enjoy the learning.
And lastly, after watching many Fleming Venture blog videos of course I'd love a 65 footer. But I thought I'd give you my reasoning for not wanting one after all (please note, I don't have the money for one and all its ensuing costs). For me and my wife, having only two to handle a boat that size is a no-go. There is no way as I age that I would not hire people to run the boat. But for me, running the boat, the galley, the everything is part of boating. Yes I would stand watches at three and four in the morning (ex Navy).
Julia Andrews of Sound of Music fame used to own a large yacht with crew. She would send the boat out from England to arrive in Campbell River BC. Then Julia would fly out from Jolly Old E and meet up with the boat to go to Desolation Sound, the Broughtons, Alaska, etc. For me that isn't the kind of boating I want to do, I would want to bring the boat from England to Campbell River, but for Julia, I'm sure she was thrilled with her experience.
Do I want to hire people to work the boat, for me and my thinking, if I was hiring, a minimal of 3 would be best on a 65 boat. But I don't want to be involved with business, and hiring and being responsible for another person's well being in a fiduciary relationship is business. Boating for me is a "no business" event. What if I don't like one or more of the people, what if they don't like me?
Where am I going to moor such a large boat, in my part of the world, this is a real issue. And I don't want to moor my boat far enough away from the cruising areas I enjoy so that getting there and returning is a hassle (translation: time). I want to be almost there in my car, then finish it off on the boat.
Many marinas have limited space for larger vessels, much more so where I am, maybe not so much where you are. So "for me," smaller is better than bigger.
And this last issue is something that only some will relate to, but its my connection with the ocean underway on smaller boats. When I took a ten day cruise from Baltimore, I and my family were on the 10th deck or something like that, spent most of the day enclosed or really unable to visually connect to the ocean.
On the Canadian destroyer I was on back oh so many decades ago, I was on a ship with no portholes. Unless you were on the bridge, in so many ways you weren't connected to the water:
https://en.wikipedia.org/wiki/HMCS_Chaudière_(DDE_235)#/media/File:HMCS_Chaudiere_1964.jpg
But when canoeing, sailing boats under 40 feet and currently on my 29 foot express cruiser, I'm only five or six feet above the water, I feel connected. I'm not sure I would have that same connectedness on a 65 foot vessel. This feeling is somewhat akin to those who prefer to cruise at 7 knots, they want to see what is going on, not feel they are some kind of metaphorical Interstate trying to get somewhere fast.
But this is me and not you, you need to find out who you are.
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Then similarly amazed how little you know. 
That's what it takes. Days of courses, days of hands on training, months and years of growth in your new profession. 
