Mikimoto pearls are excellent pearls, from what I've heard. Very expensive and very high quality. I think it would be a shame to keep them hidden away only to be taken out for special occasions. I know people who do this because they don't want them to get ruined, but I think if you're careful that wearing them a lot would be wonderful. Plus, it sounds like they have a lot of good feelings and memories attached to them, so every time you wore them you could think of those things.
I'm not sure what you should do with them exactly though, since I'm no pearl expert. I'll let the other pearl wearing ladies and Angie give you advice about that. But I say go for it--wear them!