Focal Length for 1st 2" EP?

I have my much anticipated 2" Everbrite diagonal on the way, and I'm trying to settle on the 'best' choice of focal length for my first 2" eyepiece choice. I have a Nexstar 11GPS, the stock 1.25" diagonal, and the Celestron Plossl promo set. I'm ready to spend around $250, and don't mind a slightly used bargain here. A couple of my points of indecision come from not knowing where the best advantages of the 3/4" gain show up. Field of view? Brightness? The obvious question of 'what do I want to observe?' kind of hinges on the answer to the first point. I love planetary viewing, but spend more time on DSOs. Thanks in advance for the advice.

Clear skies,

Shawn

"A couple of my points of indecision come from not knowing where the best advantages of the 3/4" gain show up. Field of view? Brightness?"

Field of view. As you go from short focal length eyepieces to longer focal lengths you see more and more sky in your eyepiece until finally the amount of sky the eyepiece can deliver to your eye is limited by the barrel diameter of the eyepiece. With 1.25" plossl this begins to happen at an eyepiece focal length around 32mm and higher. You'll notice that 35-40mm plossls with a 1.25" barrel have a smaller apparent field of view for this reason (same amount of sky shown at a lower magnification). Also, the wider the apparent field of view of an eyepiece design, the lower the eyepiece focal length where this begins to happen.

The 2" barrel will let you see more sky if you choose a focal length/field-size combination that would be barrel limited in a 1.25" barrel. In practice, this means plossls over 32mm, wide fields over ~25mm and Naglers over 16mm. I'd go for the gold and get an eyepiece that shows the widest patch of sky possible in a 2" eyepiece, like a 55mm plossl or a 40mm University Optics MK-70. Its really going to help you view extended objects in such a long focal length scope. Try out one of the eyepiece calculators online and see for yourself.