I'm working on a similar project, although it's just for myself

I just bought the frames today, in fact - and have matting material, and printed pictures, at home waiting for completion.
I took these pictures without intending for them to be black and white, but I did learn some stuff while processing them. First, are you able to do some basic postprocessing in photoshop or similar??
Lighting is really important when shooting. Cardinal rule in all siatuations, but can really make a difference in B/W work. You want your subject lit, but the background dark. Fortunate or good postprocessing can help you enhance a situation that may not be perfect.
kols by
John Bixler, on Flickr
One of the advantages I found in working with B/W images is there are less complications to postprocessing. Simply using the brightness/contrast slider can go a long ways for you. Push the contrast as high as it will go, at least that works for me.
Image composition is important. You can end up with a lot of negative (empty black space) which can create some really visually interesting pictures
Wren black and white by
John Bixler, on Flickr
I like to rely on the rule of thirds - put the subject, or most interesting part, of your picture 1/3 of the way across the pic (not 1/2). I find I naturally place my subject on the right 1/3 line, when looking at the picture.
I purposely went for a more "grimey" look in my pictures, but I've seen others do a very "silky" black and white, that is very effective as well.
Because you are shooting with the intention of doing B/W, I do think that changes how you choose where to shoot. Make sure your background is clean, again this maximizes the negative space and the "POP" you can give your subject. And don't be afraid of manual settings, you want the background to go away and the subject to stand out.
Good luck!
Oh, PS, one last thing. You are shooting your kids. This is both a blessing and a curse. DONT TRY FOR A PRECONCEIVED POSE!!! It does not work with kids, especially your own. Do something spontaneous, make them smile. Get a natural smile. You don't need to see their teeth. They need to be relaxed. Don't make it work.
I like to tell my kids to roar at me, as load as they possibly can. If we are in a crowded public place, even better. Then just snap the hell out of them for the next few seconds. This is why:
"Rawr"
rawr by
John Bixler, on Flickr
"The afterglow of RAWR"
after by
John Bixler, on Flickr