What's wrong with debit cards? I told them just to decline the card if there ever isn't enough money for a transaction, which won't ever be the case since there is like 20 grand in there. I have a rewards checking account that gives me 4% interest on up to $25K if I use my debit card 15 times a month for POS transactions. That gives me >$1K a year in interest I wouldn't have earned at any other bank. (Most other non-rewards savings/checking are like 0.000005% interest).
I use a credit card for any online purchases or any purchases where the card leaves my sight. It's pretty easy to rack up 15 POS transactions in a month. 4 or 5 trips to the grocery store, 2 trips for dog food, 4 trips for gas, and 4 or 5 other misc. transactions.