It is something I have considered. My area has exposure to tornados, potentially the effects of an earthquake, and nuclear radiation. Floods are not an issue unless it was Noah's flood. The primary danger is looting and fire following a natural disaster.
If I had to evacuate for an indefinite period of time, anything with a value under $300 would probably get left. The rest would be loaded up in a van or inside a trailer.
Rubbermaid tubs come in very handy and I keep a good supply of them available. Handguns would probably be layered between clothing inside the tubs or in hard cases. Most of the long guns would be in cases.