You may wish to visit your local Chapters/Indigo and find some books by John Vigor. He has lots of interesting things to say about what type of boat may suit your desires to sail around the world. There are also quite a few blogs about families, and couples that are doing this as well.
If you are truly minimalist and want to sail the ocean, check out Bika's blog: Home - Bika
... I own a Contessa, and I find it hard to comprehend how they are doing what they're doing on the same boat, yet they are and have been for years. I will hazard a guess that you can't do more with less like they do. I enjoy cruising on my small boat, but I could not live in her unless I was alone and not frequenting society. Here's a second video log of a fellow that just crossed the Atlantic twice in his 26' Contessa Red Admiral Trans Atlantic Part I.dv - YouTube
: This gives you some REAL WORLD footage of what it's like, how the ocean can be, and how living on a small vessel is (even if just for a short time). If that doesn't convince you that you and your wife require a larger vessel, I don't know what will. :-)
You should check out the Volvo Ocean Race video's from the past and the current; The footage gives you some ideas of what ocean seas can be like.
Lastly, in fun, you must be from a few hundred years in the past... these days, we sail around the world, not across it. ;-) Watch out for the edge of the world, there be dragons.