Update: The damage to my car wasn't quite as bad as initially thought, and given it's condition and pretty low miles, the cost to fix isn't even 70% of its value, so they're going to repair it (USAA would have gone as high as 100% private party value given its condition).
So, it looks like I won't be buying another vehicle right away. Will still be keeping my eyes open for a good deal on something (still likely an '03 or '04 Sequoia), as I'm still thinking I'll be buying something else by next summer. Not sure if I'll keep or sell the Civic at that time; we'll have to wait and see.
Thanks for the replies so far!