Some great suggestions have been given. If I had a check-in bag, the most I'd probably do is put in a Classic or other small SAK.
Times I've had to go knifeless:
Going to a courthouse;
Going to a zoo or other amusement park;
Going to a sporting venue;
...and the last time I took a plane, which was in 2003, and had to go a few days without any knife. I only had a carry-on and no check-in bag/case. BTW, the reason I haven't flown since has nothing at all to do with not being able to carry a knife; it's because I haven't had any reason to board a plane since then. If I did, such as a vacation of a lifetime thousands of miles away, I would go knifeless again in a heartbeat. Yes, I do remember being able to carry my SAK Spartan on planes with me in the past. No, I do NOT like being without a knife. No, I do NOT think that the rules prohibiting small penknives or SAKs on planes are reasonable or intelligent. BUT sometimes if you want to enjoy certain things in life (not to mention if it's a necessity, such as business trips), there will be a sacrifice. I will not miss out on something truly important to me because I can't take my pocketknife with me. When I'm really old (if I am so lucky), I don't want to be thinking, "Well, I missed out on this, this, and that, but at least I had my knife in my pocket."
Jim