You won't be able to convert your miles to another airline currency. You have a couple options that I can think of. First, AA will let you upgrade one way for 15k AA miles + $75 co-pay. You can call AA and ask them if the upgrades are available prior to purchase. Depending on when your flights are this might be available. I don't know if a ticket purchased via a
travel agent can be upgraded this way....so you might want to book it yourself online if you go this route.
If there is saver awards available only one way you can always split the reservation into (2) one ways and use miles one way and cash the other. A saver award on AA in domestic first class should be 25k one way, per person.
EDIT: I saw your second post after replying to the first. Just an fyi, purchasing miles directly from the airline is usually a terrible value. The price you pay will be close to, if not more, than the actual ticket's cost if you just paid cash. I'm not sure when you are looking to travel, but there are MANY dates in the near future where Delta has first class NYC to MCO for $228 each way. Sometimes paying cash is a better "value" than using miles/points. I would almost never use any of my points when I could outright buy the ticket for that price.