I would just let them do what they want. They'll come out eventually. Just open the door in the a.m. and close it at dusk. The chickens could very well be the draw to the outside world for them though. That's a good idea. Try dried mealworms as a lure out of the coop, and a lure back into it. They're expensive, but were a sure-fire way for me to get their attention. Use sparingly.
. I love guineas, but I like my money, too! My guineas never got excited about white millet, which was too bad! So much less expensive.
When they do come out, unless you want them to roost in trees, teach them to go back into the coop at night by herding them back in. You can use two 6-8 (whatever you can handle) foot sticks to do this, or a handy spouse (two people works better than sticks in my opinion). Go slow and don't rush them. Do this at dusk, before they get the idea that trees are for roosting. You may have already been planning that though.

When they do come out, unless you want them to roost in trees, teach them to go back into the coop at night by herding them back in. You can use two 6-8 (whatever you can handle) foot sticks to do this, or a handy spouse (two people works better than sticks in my opinion). Go slow and don't rush them. Do this at dusk, before they get the idea that trees are for roosting. You may have already been planning that though.