When it comes to which credit card to use for specific transaction, do you always try to maximize rewards, or do you try to heavily use some of your accounts in order to solidify your relationship with that bank?
IMO, pyramiding is just too much of a pain in the butt to keep track of. I just go for the occasional "new card," while keeping the original TLs a growin'
I'm all about the rewards. 
E.g. Discover's giving me 2% on everything up to a $500 for all of August, plus 5% on gas this quarter (up to $1,500).
My usual go-to cards for those kinds of purchases (netting 1% on everything and 4% on gas) stay in the wallet until I reach the cap or the promo ends. It can be complicated, but I don't mind... the pennies add up.
I PIF, always, so APRs never factor into it...
hth