Having that much space on my credit cards would allow me to move or move people quickly. Even if I have the funds in my investment accounts, it usually takes a few days to shift funds for access. I found out recently that US Savings Bonds are not as liquid as they used to be. (Most banks won't cash them unless you have an account there - They're backed by the US government! - unless you have an account, and in some places, you have to have an account for at least six months.)
If nothing major happens, I'll save all that interest.