[Wavytone]

On the scope - aperture and focal ratio, and what you want to look at...

... anything shorter than 10 mm is pointless on a f/15 scope, while anything longer than 35mm is pointless on an f/7. And I somehow don't see much point in putting a Nagler 31mm V on a Tasco 60mm refractor or 4" Newtonian.

On any given scope it usually turns out that the useful range of eyepiece focal lengths usually spans a range of perhaps 4:1 between highest and lowest. Using ratios around 2:1 from one eyepiece to the next means three eyepieces should cover the range - 4 definitely will, and 5 are unwarranted, especially when a zoom will cover at least half the range.

For double stars, lunar and planetary, the priorities are sharpness, high transmission and no ghosts - a wide field is not important, so spending big $ on a set of Naglers is a waste when you really want a set of Monocentric's or at least orthoscopic. Plossl would do but they aren't the best. The fewer the elements the better, too.

For rich field observing, a high apparent field of view field and sharpness to the edge are priorities, several to choose from in the TV range.