Depends on where you got your "reasonably good rate." I'm assuming that it's from the PC/IC website as you're asking for a discount or corporate code. If not, and your rate is from Priceline (which does offer a pretty good rate if you bid right) or most any other discount source (read "non-PC/IC website reservation"), then you shouldn't expect to get any points.

Often getting a special discount rate is a matter of "adding" a category to the rate selection dropdown list. This can be done by finding and accessing a promotion on the PC website or on the specific hotel page and finding the link for "hotel specials/offers." I just checked and the Crowne Plaza Tokyo (Ikebukuro Metropolitan) doesn't appear to have any of these offers just now.

As for joining PC, it's not a bad idea at all if you're not already a member, as even basic members get some perks. Signing up can be done at the same time you fill in your "Guest Information" on the reservations page.

And with that comment, I shall end this, my 1000th post on FT. Glad it could be on the PC/IC Forum.