Yes, I play the float game all the time. Why not take the free cash. Of course, like mentioned above, I don't push it too far since the penalty for paying late is great. Thus, I don't pay things on the day they are due, I pay them on the last date for which I can detect a problem and still have time to fix it without going late. That usually means 5 business days before it is due.
I'll do a simple example to show what I do.
1) I have a 6% loan that I am paying off. I want to pay it off as soon as possible.
2) Suppose I wanted to buy a $200 item.
3) I have four choices (sorted from worst to best):
(a) pay cash (which means withdrawing money previously),
(b) debit card if I had one (which means paying it immediately),
(c) credit card near the end of the billing cycle,
(d) credit card near the begining of the billing cycle.
Lets analyze the situations.
(a) Pay cash. Lets say I took out $100 in cash 2 weeks ago. That means I couldn't have that $200 paid on my loan for 14 days. At 6% interest, taking out that cash early cost me 23 cents.
(b) Pay with debit card (if I had one). Since the payment is instant, this has no float effect. It is break even.
(c) Pay with a credit card near the end of the billing cycle. This gives me ~3 weeks until the bill is due, but since I pay the bill 5 days ahead of time, lets just round down to 2 weeks. 6% interest for 2 weeks gains me 23 cents.
(d) Pay with a credit card near the beginning of the billing cycle. This gives me 4 weeks until the bill comes AND a 3 week grace period. Subtract 1 week for paying a bit early and I net 6 weeks of free interest. That comes to 70 cents in free money (compared to debit cards).
So I can either pay $100 + $0.23 = $100.23 or pay $100 - $0.70 = $99.30 for the exact same item. That is a swing of nearly $1 for a $100 purchase. In other words, I get nearly 1% back on every single thing I buy just based on the float game. That is on top of the 3%-5% cash back I get from the credit card.
Think how many purchases you make. Think what 1% will do for you.