Re: buying advice?
The reality is that there are a great many boats in the 40 to 50 foot range that would meet your needs and if the people on this board were to suggest six suitable ones there would be a hundred others that would be missed. Time spent on yachtworld.com using different search parameters is well worth it since you can see what style of boat appeals to you: rig, hull material, interior arrangements, general aesthetics, etc. Also, it makes considerable sense to talk about displacement rather than length since two fifty footers are hugely different if one is 12 tons and another is 25 tons.
Seems like you are in a good situation with six on/six off. We met an Aussie in Tahiti who worked in the mines for 5 weeks on and 5 off. When his shift ended he hopped on a plane to his boat. If you six months you could do some serious cruising since in areas with tropical cyclones (eg Caribbean and much of the South Pacific) you have to leave the area for many months at a time.
If you have to ask about maintenance of a wood boat you don't want one. Stick to fiberglass, steel, or possibly aluminum although the latter are rare outside France.
Finished the circumnavigation in early February in Grenada. Have to work on a book project for the next several months so the boat will be waiting for next year.