This is not the best use of miles IMHO. Not to question your choice of a vacation destination, but that is a 35K RT ticket per person = 210000 miles to take a family of 6 there. Depending on how you value miles, that is at least $8500 in miles if not more. You can *certainly* buy tickets for less to get there. I did a search for some random dates in February and tickets MSY-NAS were $380 each. Not only will it be extremely difficult for you to find 6 award tickets on the same flight, but you may have to fly significantly out of your way to do it.
If you timed your trip with one of your husband's trips to Thailand, you could go to Hawaii for fewer miles (5x award tickets at 40K each and your husband stopping in HNL en-route to BKK). While finding 6 tickets on the same flights will also be a challenge, it won't be impossible because United has many more flights to Hawaii than to the Bahamas and I've seen that MSY-LAX and MSY-SFO flights are often fairly open for awards.
Finally, worth noting in case your husband isn't aware, United is ending their service to BKK. He will still be able to fly United to Tokyo and connect from there on partner airline ANA, but it won't necessarily be as cost-effective or comfortable to do it (no Economy Plus, less 1K recognition etc). I'd encourage considering a look at Delta (MSY-NRT-BKK all on Delta metal is possible).