With boats in the 30 foot and above range, I say wind is public enemy number one.
These boats can handle alot of swell. But wind, like 15 knots and above, just makes a mess of everything. White caps, blown fishing lines, windshield wipers - yuk!
I have learned to do my trips in under 15 knots of wind - preferably under 10 knots.
And the above Poster is spot on as to the swell and period. Look for a 2:1 ratio where the interval is 2X the swell height.
And remember, it's never calm for very long, not rough. So if you don't like what you see in the weather forecast - simply wait...
With respect to being offshore - another factor to consider is - can you comfortably plane the boat for the long ride home? If you cannot - you will burn much more fuel pounding through that crap in displacement mode. So weather becomes a consideration for your fuel plan. These boats are designed to plane. If you're offshore and the white caps hit with a 1:1 interval to swell, you could be in a bit of trouble fuel wise (let alone comfort) for the ride home. Good question and good luck!