A plossl is a good choice of eyepiece. Get the best you can afford, and try them first if possible. The 20mm with this is adequate. My suggestion is to get eyepieces in this order, as you can afford them. 9-15mm, in that range. 17-25mm range. 32mm or close to that. 2x or 3x barlow of decent quality, then a 4-6mm. Avoid the really low end stuff, and get a decent Celestron, Meade or Orion and you can't go wrong. Your eyepiece collection can stay with you if you decide to get a better scope and sell this one, so it pays to chose decent ones.