I was about to suggest looking at the mAh of the batteries, but Tom beat me to it :(
I used to use 800mAh which didn't last long, but I now have some 2100mAh, which last much longer. (That 28,000 should read 2,800 in Tom's post by the way :P )
The time taken to re-charge your batteries depends not only on the state of your batteries (fully dis-charged, half-discharged, etc), but also on the charger that you're using.
I recommend that you invest in a good charger. It might be a costly initial outlay, but it'll only be a one-off and it will be well worth it. The charger that I used to use, took approx 8 hours to charge my 800 mAh batteries. I now use a charger that automatically stops when the batteries are full and take approx 45 mins to charge my 2100mAh batteries. I charged some 800mAh earlier today and they took approx 10 mins to charge from fully-discharged ...... I rest my case!
Them 2500mAh that Tom recommends seem a good buy, but have a look on Ebay too - there's many a bargain to be had on there.