Absolutely no reason whatsoever to close it! You would never want to lose a CL that high. I would treat them as a PIF'er. If you're determined to carry a balance, do so on other cards. After about six months of barely using the Discover, and always PIF'ing before your statement date, call up and ask if they can go ahead and give you a better APR.
But this works best if you show that you don't need a low APR, by not carrying balances on any cards. If they think that they can make some money off of you with a high APR, they will certainly do so. Right now, they don't have any incentive to lower it, if that makes sense.
* Credit is a wonderful servant, but a terrible master. * Who's the boss --you or your credit?
FICO's: EQ 781 - TU 793 - EX 779 (from PSECU) - Done credit hunting; having fun with credit gardening. - EQ 590 on 5/14/2007