For planets, to get the best available Plossl, try reading the description of the Televue 11 mm Plossl on the Astronomics website (under accessories at astronomics.com ). If you can afford $85 to $120 eyepieces, Televue's Plossls do outperform generics at least slightly.
I keep mentioning Plossls. That's only because of their good cost/performance ratio. There are innumerable types of fine eyepieces. Do upgrade from the SMAs.
Please also read my post under the "eyepieces" section of astronomy.net, in the thread "very low power eyepieces." It explains why I recommend a certain set of low powers. For an 8-inch scope, I wouldn't try to go below 40 power, for reasons explained there. The link is
http://www.astronomy.net/forums/eyepieces/messages/392.shtml