No, actually it doesn't bother me to spend a couple of minutes waiting. Gives the soldering iron time to warm up, have a think about what I'm doing etc... then again, I'm semi-retired as an amp tech now and I'm not exactly rushed off my feet (except by my two-year-old daughter!).
I'd agree with anything over 1K. That limits the initial current to 0.5A from a 500V power supply (and it drops below that immediately of course), which is OK.
Actually, the best way to discharge the caps is to run a straight jumper wire from the #1 pin on the first preamp tube to the chassis ground, then switch the amp on (after unplugging it of course). The uses the full resistance of the amp to drain the caps nice and slow.